Sunni vs. Shia Islam

Sunni and Shia Muslims pray toward the same Kaaba, recite the same Qur’an and fast in the same month of Ramadan. Yet for almost the whole of Islamic history they have been distinct communities, with their own hadith collections, schools of law and scholars. Newspapers often reduce the difference to a "sectarian" rivalry between Iran and Saudi Arabia. That is too thin. The division began with a disagreement about who should lead the Muslim community after the Prophet Muhammad died in 632, and it became a disagreement about religious authority itself: who may speak for God and the Prophet once the Prophet is gone.

This article sets out what each tradition believes, as far as possible in the words of its own sources: Sunni hadith collections and creeds, a standard Twelver Shia statement of faith, and academic reference works. Christians should be able to describe each side in a way its members would recognize. A short Christian reflection comes at the end, kept modest on purpose.

In brief

About 87 to 90 percent of the world's Muslims are Sunni and 10 to 13 percent are Shia, according to the most widely cited estimate (Pew Research Center, 2009). The two share belief in one God, Muhammad as the final prophet, the Qur’an, the basic practices of Islam and the Day of Judgment. They divide over leadership after Muhammad. Sunni Islam holds that the community rightly recognized Abu Bakr as the Prophet's first successor, followed by Umar, Uthman and Ali, the four "Rightly-Guided" caliphs. Shia Islam holds that God, through the Prophet, designated Ali ibn Abi Talib and a line of Imams from his family, and the Twelver Shia, the largest branch, hold these Imams to be protected from error. The killing of Ali's son Husayn at Karbala in 680 became the defining memory of Shia piety. From these roots grew different hadith collections, legal schools and some differences in practice. Each side argues from texts the other also accepts. In 2005 Sunni and Shia scholars, through the Amman Message, recognized the followers of each other's legal schools as Muslims, though surveys show mutual suspicion remains strong in some countries.

Thesis: The Sunni–Shia division is a genuine and long-standing disagreement about religious authority after Muhammad, neither a modern political invention nor a dispute about the basic pillars of Islam, and each tradition deserves to be described in its own terms before anyone draws conclusions from it.

How many Sunnis and Shia are there?

The figures most often quoted come from the Pew Research Center's 2009 report Mapping the Global Muslim Population. It estimated "between 154 million and 200 million Shia Muslims in the world," and concluded that "10-13% are Shia Muslims and 87-90% are Sunni Muslims." Pew noted that data on sectarian affiliation "have been infrequently collected or, in many countries, not collected at all," so these are broad, and now dated, estimates.¹

The same report found that Shia Muslims are a majority of the population in four countries, "Iran, Azerbaijan, Bahrain and Iraq," and that "most Shias (between 68% and 80%) live in just four countries: Iran, Pakistan, India and Iraq."² Most Muslim-majority countries are majority Sunni. Many Muslims use neither label: Pew's later survey of 39 countries and territories found that in Central Asia most Muslims, and in southern and eastern Europe pluralities or majorities, called themselves "just a Muslim," as did 56 percent in Indonesia.³

The question of 632: who should lead?

As Pew puts it, "Sunni and Shia identities first formed soon after the death of the Prophet Muhammad in 632 C.E."⁴ No one could inherit Muhammad's prophethood, which Muslims believe ended with him, but someone had to lead.

Saqifa and the Sunni account

According to Sahih al-Bukhari, the most respected Sunni hadith collection, the Medinan "Helpers" (Ansar) gathered in the hall of the Banu Sa'ida (the saqifa) to choose a leader. Abu Bakr and Umar went to them, voices were raised, and Umar pledged allegiance to Abu Bakr, "and then all the emigrants gave the Pledge of allegiance and so did the Ansar afterwards." The report comes from a sermon Umar gave years later, and it is unusually frank. Umar concedes that "the pledge of allegiance given to Abu Bakr was given suddenly and it was successful. No doubt, it was like that, but Allah saved (the people) from its evil," and he adds a rule for the future: "whoever gives the pledge of allegiance to anybody among you without consulting the other Muslims, neither that person, nor the person to whom the pledge of allegiance was given, are to be supported." He also records that "'Ali and Zubair and whoever was with them, opposed us."⁵

Sunnis see this as the community acting together, under pressure, to recognize its most deserving member. As Wilferd Madelung summarizes the Sunni case, Abu Bakr was the most excellent of men after the Prophet, and the Prophet had shown his preference by ordering him to lead the prayers during his final illness.⁶ Sunnis also point to the Qur’an's praise of believers "whose affair is [determined by] consultation among themselves" (Qur’an 42:38, Sahih International).⁷ The classic Sunni creed of al-Tahawi (d. 933) states the settled view: "We confirm that, after the death of the Messenger of Allah ... the caliphate went first to Abu Bakr al-Siddiq ... then to 'Umar ibn al-Khattab ... then to 'Uthman ... and then to 'Ali ibn Abi Talib ... These are the Rightly-Guided Caliphs and upright leaders."⁸

The name "Sunni" is short for ahl al-sunna wa'l-jama'a, "the people of the Prophet's practice and of the community." In Sunni thought no individual inherits the Prophet's religious authority. It lives in the Qur’an, the Prophet's Sunna as recorded in hadith, the consensus of the scholars and the recognized schools of law.

Ghadir Khumm and the Shia account

Shia Muslims begin from a different event. Shortly before his death Muhammad addressed his followers at a watering place called Khumm, between Mecca and Medina. The saying most associated with that occasion is preserved in short form in the Sunni collection of al-Tirmidhi (which does not name the place), and Sunni hadith scholars such as al-Albani grade it authentic: "For whomever I am his Mawla then 'Ali is his Mawla."⁹

The word mawla can mean master, patron, guardian, friend or ally. Shia scholars read the saying as appointment to leadership; Sunni scholars as a declaration of the loyalty owed to Ali, not a nomination to the caliphate. Shia writers also point to other texts in Sunni collections: the Prophet's words to Ali when he left him in charge of Medina, "Will you not be pleased that you will be to me like Aaron to Moses? But there will be no prophet after me";¹⁰ and the sermon at Khumm reported in Sahih Muslim, in which the Prophet says, "I am leaving among you two weighty things: the one being the Book of Allah ... The second are the members of my household."¹¹ From the Qur’an they cite 5:55, on those who "give zakāh, and they bow [in worship]," which Shia exegesis applies to Ali, and 33:33, on God purifying "the people of the [Prophet's] household."¹²

The Iraqi scholar Muhammad Ridha al-Muzaffar (1904 to 1964), in his much-reprinted Twelver creed 'Aqa'id al-Imamiyyah, calls the Imamate "a continuation of prophethood" and concludes that "Imamate cannot be decided without a commission from Almighty Allah conveyed to us by the Holy Prophet (s) or the previous Imam (`a). Imamate is thus not subordinate to selection or choice by the people."¹³ The name Shia comes from shi'at Ali, the "partisans of Ali."

What both sides' sources admit

Sahih al-Bukhari also records, on the authority of Muhammad's widow Aisha, that Ali did not give his pledge to Abu Bakr during the six months that Fatima, the Prophet's daughter and Ali's wife, lived after her father. When he did, he told Abu Bakr: "you did not consult us in the question of the rule and we thought that we have got a right in it because of our near relationship to Allah's Messenger." Abu Bakr wept, and Ali then gave his pledge publicly.¹⁴ Sunnis read this as reconciliation; Shia as a rightful claim pressed and then set aside. Either way, {{strong: the earliest sources of both communities agree that the succession to Muhammad was contested from the first days.}}

Madelung begins his study: "No event in history has divided Islam more profoundly and durably than the succession to Muḥammad."¹⁵ The question is whether leadership was God's appointment or the community's choice, and so whether the first three caliphs ruled by right. The site's article Who Was Supposed to Succeed Muhammad? examines this evidence in more detail.

Karbala: when a dispute became a sacred memory

Ali ruled as caliph from 656 until his assassination in 661.¹⁶ Power then passed to the Umayyad dynasty. When the caliph Yazid demanded allegiance, Ali's younger son Husayn, the Prophet's grandson, refused. According to the Encyclopaedia Iranica, Husayn, "with a party of seventy-two armed men and some women and children," was on his way to Kufa, whose people had invited him to lead a revolt. At Karbala his party was surrounded by a force of about 4,000, and on 10 Muharram 61 (10 October 680) Husayn and all his able-bodied male companions were killed; the women and children, including Husayn's son Ali, later the fourth Imam, were taken prisoner.¹⁷

For Shia Muslims Karbala is the central story of righteous suffering. Meir Litvak writes that it "became the constitutive event of Shiʿism as a religion."¹⁸ By the ninth century the Imams were already encouraging visits to Husayn's tomb on the tenth of Muharram, Ashura, and on the fortieth day after it, Arba'in, and both remain central to Shia devotion. Forms of mourning vary. Bloodletting with blades (tatbir or qama-zani) is practiced by some, but Shia jurists are divided over it: the Shia reference work WikiShia notes that some leading authorities permitted it, while others, including Sayyid Abu l-Hasan al-Isfahani and, in 1994-95, Iran's Supreme Leader Ali Khamenei, opposed it.¹⁹

Sunni Muslims also honor Husayn as the Prophet's grandson, but Ashura carries a different meaning for them. Sahih al-Bukhari records that the Prophet fasted on the day of Ashura, which the Jews of Medina kept in memory of God's rescue of Israel through Moses, and that after the Ramadan fast was prescribed the Ashura fast became optional.²⁰

Religious authority: caliphs, Imams and scholars

The Twelver Imams

The largest Shia branch, the Twelvers (Ithna 'Ashariyya), recognize twelve Imams: Ali, his sons Hasan and Husayn, and nine of Husayn's descendants, ending with Muhammad al-Mahdi. Al-Muzaffar's creed teaches that "an Imam, just like a Prophet, must be infallible from all vices and defects ... from childhood up to death."²¹ The Imams are rightful rulers and also authoritative teachers of the faith.

According to the official Twelver account, the twelfth Imam entered occultation (ghayba) when his father, the eleventh Imam, died in 874. Saïd Amir Arjomand explains that the "lesser" occultation, from 874 to 941, was the period "when the Hidden Imam communicated with the community through intermediaries"; the "greater" occultation followed and continues. After the eleventh Imam's death his followers had split into fourteen groups.²² Najam Haider describes how this crisis led Twelver scholars to rethink the Imamate and consolidate a distinct identity.²³ The hidden Imam is expected to return as the Mahdi and fill the earth with justice.

Scholars in the Imam's absence

In the Imam's absence, Twelver Shi'ism gives qualified jurists (mujtahids) a strong role. Al-Muzaffar writes that "a well-qualified mujtahid is a representative of the Imam during the age of occultation," and ordinary believers follow (taqlid) the rulings of a living jurist.²⁴ The most senior are known as a marja' al-taqlid, "source of emulation," an institution found across the Twelver world, not only in Iran.

Iran goes further with the doctrine of wilayat al-faqih, the guardianship of the jurist, which its constitution adopts. Shia scholars disagree about it: WikiShia lists Ayatollah Khomeini, who set out the theory at Najaf in 1969, among its proponents, and al-Shaykh Murtada al-Ansari, Akhund al-Khurasani and Sayyid Abu l-Qasim al-Khoei among its opponents.²⁵ Iran's system is not simply "what Shia believe."

Other Shia branches

Not all Shia are Twelvers. The Zaydis take their name from Zayd ibn Ali, Husayn's grandson, whose revolt in 740 is often treated as the moment they separated.²⁶ For Zaydis an Imam may be any righteous, learned descendant of Fatima who rises against unjust rulers. WikiShia describes them as "closer to Sunnis, in comparison to other Shi'a branches," and notes that Yemen has the largest Zaydi population; Zaydi Imams ruled there until 1962.²⁷

The Isma'ilis separated from the Twelvers' line over the succession to the sixth Imam, Ja'far al-Sadiq, in 765. Nizari Isma'ilis follow a living, present Imam, the Aga Khan. Musta'li Isma'ilis, including the Dawoodi Bohras, believe their Imam went into concealment in the twelfth century and are led by a da'i who acts on his behalf.²⁸ Pew also lists the Alawites of Syria and the Alevis of Turkey among the Shia,²⁹ but their beliefs differ considerably from Twelver Shi'ism, and how to classify them is disputed.

Different hadith, different law

For Sunnis, the most authoritative hadith collections are the two Sahih collections of al-Bukhari (d. 870) and Muslim (d. 874 or 875), which Shahab Ahmed describes as "the two most important texts in Sunni Islam after the Qurʾān." Next come the Sunan collections of Abu Dawud (d. 888), al-Tirmidhi (d. 892), Ibn Maja (d. 886) and al-Nasa'i (d. 915). Together these form "the Sound Six." The two Sahih collections gained their standing within about a century of their compilers' deaths; the authority of the four Sunan, Ahmed writes, "was almost universally accepted by the 6th/12th century."³⁰

Twelver Shia rely on four canonical collections: al-Kafi of al-Kulayni (d. 941), Man la yahduruhu al-faqih of Ibn Babawayh, known as al-Shaykh al-Saduq (d. 991), and the Tahdhib al-ahkam and al-Istibsar of al-Shaykh al-Tusi (d. 1067). In these the sayings of the Imams, above all Ja'far al-Sadiq, carry authority alongside those of the Prophet. The two literatures do not simply reject each other. Ahmad Kazemi-Moussavi notes that "Shiʿite authors generally acknowledge the authenticity of most of the traditions presented in the 'Six Sound Collections'," but use them "mainly ... in historical and polemical contexts rather than as proof texts in legal discussions, as long as alternative Shiʿite traditions are available."³¹ The real difference lies in whose reports count as decisive in law and doctrine.

Sunni Islam has four surviving legal schools, Hanafi, Maliki, Shafi'i and Hanbali, which accept one another. Twelver Shia follow the Ja'fari school, named after Ja'far al-Sadiq; the Zaydis have their own. In November 2004 King Abdullah II of Jordan issued the Amman Message, and in July 2005 about 200 scholars from 50 countries, meeting in Amman, issued a unanimous ruling known as its "Three Points." The first recognizes as Muslims the followers of the four Sunni schools, "the two Shi'i schools of Islamic jurisprudence (Ja'fari and Zaydi)," and the Ibadi and Zahiri schools, and forbids declaring them apostates. Ayatollah Sistani was among the senior scholars whose rulings informed it, and more than 500 scholars eventually endorsed it.³²

What differs in practice

• Combining prayers. Both traditions pray the same five obligatory prayers, but Shia usually combine the noon and afternoon prayers, and the sunset and night prayers, while Sunnis normally pray them separately. Shia cite a report in Sahih Muslim that the Prophet "observed the noon and afternoon prayers together in Medina without being in a state of fear or in a state of journey."³³ According to WikiShia, Shia jurists still regard praying them separately as recommended, while most Sunni jurists allow combining only with an excuse such as travel, illness or rain.³⁴
• The prostration stone. Shia law requires the forehead in prostration to rest on earth or on something growing from it that is not eaten or worn, so many Shia use a small tablet of clay or stone (turbah), sometimes from the soil of Karbala. WikiShia stresses that "turbah is not essential in prostration"; it is a convenient piece of earth. Wahhabi critics regard the practice as an innovation.³⁵
• The call to prayer. In many Shia communities the call to prayer includes "I bear witness that 'Ali is the wali of Allah." WikiShia explains that "according to the majority of Shiite fuqaha, this phrase ... is not part of adhan," though it is recommended or permitted to recite it. The Shia call also includes "hurry toward the best of deeds," which the Sunni call does not.³⁶
• Temporary marriage. Twelver Shia law permits mut'a, a marriage for a fixed term; Sunni law holds that the Prophet prohibited it. The history and the arguments on both sides are set out in the site's article Mut'a: Did Muhammad Permit Temporary Marriage?
• Shrines and pilgrimage. Pilgrimage to the Imams' tombs, as at the four Iraqi shrine cities of Karbala, Najaf, Kadhimiya and Samarra, is a major Shia devotion.³⁷

What they share

The common ground is large: the oneness of God (tawhid), Muhammad as the last prophet, the resurrection and Judgment, prayer, almsgiving, the Ramadan fast and the pilgrimage to Mecca. Both use the same Qur’an. Polemic sometimes claims otherwise, but the standard Twelver creed is explicit: "The Book that we are currently holding and reciting is the very Qur'an that was revealed to the Holy Prophet."³⁸ Questions about the Qur’an's textual history therefore apply to both communities equally; see Has the Qur’an Been Perfectly Preserved?

Both also expect the Mahdi. A report in the Sunni collection of Abu Dawud says, "The Mahdi will be of my family, of the descendants of Fatimah."³⁹ Twelver Shia identify him with the hidden twelfth Imam; Sunnis who accept such reports do not.

Why the division still matters

Sunni–Shia language is often used to explain wars in Iraq, Syria, Yemen and Lebanon. Religious identity matters there, but it is not the whole story. In a 2014 Brookings paper F. Gregory Gause III framed the Saudi–Iranian rivalry as a regional cold war. As Brookings summarizes his argument, "Rather than stemming from sectarian rivalry, this new Middle East cold war results from the weakening of Arab states."⁴⁰

Mutual suspicion is real too. Pew's 2012 survey found that in the Middle East and North Africa, "in most countries surveyed in the region, at least 40% of Sunnis do not accept Shias as fellow Muslims," although in Iraq and Lebanon overwhelming majorities of Sunnis did accept Shia as members of the same faith.⁴¹

The strongest objections each side makes

The Sunni question to the Shia

If Ghadir Khumm was a public appointment, why did the leading Companions, weeks later, debate the leadership at Saqifa as though none existed? Why did Ali, in the report preserved by al-Bukhari, ground his claim on "near relationship" rather than on designation, and then pledge to Abu Bakr? And the Qur’an never names Ali.

Shia answer that the Companions' failure does not cancel the Prophet's command, and that Ali's restraint was chosen for the sake of Islam. Al-Muzaffar writes that although Ali believed his right had been usurped, "his behaviour with them was full of tolerance," and that he did not press his designation publicly "until the leadership of the Muslim nation eventually returned to him."⁴² They also argue that the cumulative weight of Ghadir, the "two weighty things," the Aaron saying and the Qur’anic verses on the household, all found in Sunni sources, points one way.

The Shia question to the Sunnis

The Prophet gave detailed rules for prayer, inheritance and marriage; why would he leave no instruction about the office that would shape everything else? Umar's own sermon admits that the pledge to Abu Bakr was sudden and that Ali's party opposed it. How can a choice made in haste, without the Prophet's household, carry religious authority?

Sunnis answer that the Prophet's silence was itself the instruction: the community was trusted to consult, as the Qur’an commends, and its consensus around Abu Bakr was confirmed by the Companions, in the end including Ali. They add that the doctrine of infallible Imams rests on reports Sunnis do not accept, and that during the long occultation Twelver Shia are in practice guided by fallible jurists, as Sunnis are.

An objection to Christian use of this division

A Christian may be tempted to say that the Sunni–Shia split shows Islam to be false. Muslims rightly reply that Christians are divided too: after Ephesus and Chalcedon in the fifth century, in the estrangement of Rome and Constantinople conventionally dated to 1054, and at the Reformation. That reply is fair. Division alone proves nothing about the truth of a religion.

A Christian reflection

What an Orthodox Christian can fairly say is narrower. After 632 both traditions had to answer a question every faith with a founder faces: how does the founder's authority reach the next generation? The Orthodox Church answers it differently. It holds that Christ's authority was handed on through the apostles to bishops in identifiable local churches, who met in council when the faith was disputed, as the apostles and elders did at Jerusalem in Acts 15. The Church does not claim that this prevented all division, and Catholics and Protestants contest how Orthodoxy applies it. See Did the Early Church Believe in Apostolic Succession?, the Apostolic Succession guide and Why Islam Is Not a Continuation of the Christian Apostolic Faith.

What we can say confidently

• Sunnis are roughly 87 to 90 percent of Muslims and Shia 10 to 13 percent (Pew, 2009), though sect data are incomplete and dated.
• The division began with the succession in 632; Sunni sources themselves record that Abu Bakr's selection was sudden and that Ali's party at first stood apart.
• The Ghadir Khumm saying about Ali is preserved in Sunni hadith collections; the two traditions differ over what it means.
• Husayn was killed at Karbala on 10 Muharram 61 (10 October 680), and Karbala became the defining memory of Shia piety.
• {{very-strong: Sunni and Shia Muslims use the same Qur’an and share the basic practices of Islam, while relying on different hadith collections and legal schools.}}
• Shia Islam is internally diverse, and bloodletting on Ashura and Iran's guardianship of the jurist are disputed among Shia scholars themselves.

What remains disputed

• {{debated: Whether Muhammad intended Ali to succeed him as leader of the community.}} The answer turns on how to read Ghadir Khumm and related reports.
• Exactly what happened at Saqifa and after, since the accounts were written down generations later by transmitters with their own loyalties.
• How many Shia there are today, and the share belonging to each Shia branch; no recent global count exists.
• How far modern Middle Eastern conflicts are driven by sectarian belief rather than by state rivalry and collapse.
• Whether the Alawites and Alevis should be counted as Shia.

Conclusion

The difference between Sunni and Shia Islam is real and old, and it concerns something worth caring about: where God's guidance is to be found after the Prophet. Sunni Muslims find it in the Qur’an, the Sunna and the consensus of the community; Shia Muslims in the Qur’an, the Sunna and the Prophet's household, the Imams. Both read many of the same texts and reach different conclusions in good faith. Christians who want to speak with Muslims honestly should begin by knowing which tradition their neighbor belongs to, and by describing it as he would.

The Orthodox Christian believes that the guidance humanity needs is finally a Person, the risen Lord Jesus Christ, who promised that the Spirit would lead His Church into all truth, and that this Church is still recognizable in the apostolic faith, worship and bishops it received. That conviction can be held with real respect for Muslim neighbors who ask, as Christians do, how God's word reaches us across the generations.

Notes

1. Pew Research Center, Mapping the Global Muslim Population: A Report on the Size and Distribution of the World's Muslim Population (Washington, DC, 7 October 2009), section on Sunni and Shia populations. pewresearch.org. ↩
2. Pew Research Center, Mapping the Global Muslim Population (2009), same section. ↩
3. Pew Research Center, The World's Muslims: Unity and Diversity (Washington, DC, 9 August 2012), executive summary. pewresearch.org. ↩
4. Pew Research Center, The World's Muslims: Unity and Diversity (2012), executive summary. ↩
5. Sahih al-Bukhari 6830 (Book of Limits and Punishments), report of Ibn Abbas quoting Umar, English translation as published on sunnah.com. sunnah.com/bukhari:6830. ↩
6. Wilferd Madelung, The Succession to Muhammad: A Study of the Early Caliphate (Cambridge: Cambridge University Press, 1996 [Cambridge Core print date]), Introduction (summary of the Sunni and Shia positions). ↩
7. Qur’an 42:38, Sahih International translation. quran.com/42/38. ↩
8. Abu Ja'far al-Tahawi (d. 321/933), al-'Aqida al-Tahawiyya, translated by Iqbal Ahmad Azami. masud.co.uk. The ellipses omit blessing formulas and one clause; "alKhattab" in the online text is printed here as "al-Khattab." ↩
9. Jami' al-Tirmidhi 3713 (Chapters on Virtues), English translation as published on sunnah.com; graded sahih by al-Albani (sunnah.com shows the Darussalam grade "Sahih"). The report does not name Khumm; the link to that occasion comes from other reports. sunnah.com/tirmidhi:3713. The location of Khumm "between Mecca and Medina" is from Sahih Muslim 2408a (note 11). ↩
10. Sahih al-Bukhari 4416 (Book of Military Expeditions), report of Sa'd, sunnah.com translation. sunnah.com/bukhari:4416. ↩
11. Sahih Muslim 2408a (Book of the Merits of the Companions; in-book reference 44:55), report of Zayd ibn Arqam, sunnah.com translation. sunnah.com/muslim:2408a. ↩
12. Qur’an 5:55 and 33:33, Sahih International translation, quran.com. For the Shia reading of both verses, see Muhammad Ridha al-Muzaffar, The Faith of the Imamiyyah Shi'ah, trans. Badr Shahin (ABWA Publishing and Printing Center), Part 3, "Imamate," and its notes. al-islam.org. ↩
13. Al-Muzaffar, The Faith of the Imamiyyah Shi'ah, Part 3, "Imamate." The list of printings of the Arabic original is in the translator's front matter. ↩
14. Sahih al-Bukhari 4240-4241 (Book of Military Expeditions; in-book reference 64:278), report of Aisha, sunnah.com translation. sunnah.com/bukhari:4240. ↩
15. Madelung, The Succession to Muhammad, Introduction, opening sentence. ↩
16. "ʿAlī b. Abī Ṭāleb," Encyclopaedia Iranica I/8 (1985), 838-48: "fourth caliph (35-40/656-61)." iranicaonline.org. ↩
17. Meir Litvak, "Karbala," Encyclopaedia Iranica XV/5 (2010), 550-56, citing al-Tabari. iranicaonline.org. ↩
18. Litvak, "Karbala." ↩
19. WikiShia (Ahl al-Bayt World Assembly), "Qama-zani." en.wikishia.net. ↩
20. Sahih al-Bukhari 2002 and 2004 (Book of Fasting), reports of Aisha and Ibn Abbas, sunnah.com translation. sunnah.com/bukhari:2004. ↩
21. Al-Muzaffar, The Faith of the Imamiyyah Shi'ah, Part 3, "Infallibility of the Imam." ↩
22. Saïd Amir Arjomand, "Ḡayba," Encyclopaedia Iranica X/4 (2000), 341-44. iranicaonline.org. ↩
23. Najam Haider, Shi'i Islam: An Introduction (Cambridge: Cambridge University Press, 2014), ch. 4, "Fragmentation" (chapter summary on Cambridge Core). ↩
24. Al-Muzaffar, The Faith of the Imamiyyah Shi'ah, "Prelude: Ijtihad and Taqlid," section "The Mujtahid." ↩
25. WikiShia, "Guardianship of the Jurist," including its section on the Islamic Republic of Iran. en.wikishia.net. ↩
26. Haider, Shi'i Islam, ch. 4. ↩
27. WikiShia, "Zaydiyya." en.wikishia.net. ↩
28. Haider, Shi'i Islam, ch. 4 (the 765 dispute); Azim Nanji, "Ismaʿilism xvii. The Imamate in Ismaʿilism," Encyclopaedia Iranica XIV/2 (2007), 210-12 (Nizari and Musta'li branches; the Musta'li Imam's concealment around 524/1130). iranicaonline.org. ↩
29. Pew Research Center, Mapping the Global Muslim Population (2009): "Shias include Ithna Asharis (Twelvers), Ismailis, Zaydis, Alevis and Alawites." ↩
30. Shahab Ahmed, "Hadith i. A General Introduction," Encyclopaedia Iranica XI/4 (2002), 442-47. iranicaonline.org. Death dates are converted from the hijri dates Ahmed gives. ↩
31. Ahmad Kazemi-Moussavi, "Hadith ii. Hadith in Shiʿism," Encyclopaedia Iranica XI/4-5 (2002), 447-49. iranicaonline.org. ↩
32. The Amman Message, official site: home page and "The Three Points of the Amman Message." ammanmessage.com. ↩
33. Sahih Muslim 705b (Book of Prayer: Travellers; in-book reference 6:60), report of Ibn Abbas, sunnah.com translation. sunnah.com/muslim:705b. The neighbouring report 705a (6:59) has the noon and afternoon, and sunset and night, prayers combined, without the words "in Medina." ↩
34. WikiShia, "Combining Prayers" ("Performing two prayers together"). en.wikishia.net. ↩
35. WikiShia, "Turbah." en.wikishia.net. ↩
36. WikiShia, "Adhan," text and note 3. en.wikishia.net. ↩
37. Litvak, "Karbala," opening paragraph. ↩
38. Al-Muzaffar, The Faith of the Imamiyyah Shi'ah, Part 2, "The Holy Qur'an." ↩
39. Sunan Abi Dawud 4284 (Book of the Mahdi), report of Umm Salamah, sunnah.com translation; graded sahih by al-Albani. sunnah.com/abudawud:4284. ↩
40. F. Gregory Gause III, "Beyond Sectarianism: The New Middle East Cold War," Brookings Doha Center Analysis Paper (22 July 2014). brookings.edu. ↩
41. Pew Research Center, The World's Muslims: Unity and Diversity (2012), executive summary. ↩
42. Al-Muzaffar, The Faith of the Imamiyyah Shi'ah, Part 4, section "Calling upon Islamic Unity." ↩

Bibliography

Primary sources

• The Qur’an. Sahih International translation. quran.com.
• al-Bukhari, Muhammad ibn Isma'il. Sahih al-Bukhari. English translation as published on sunnah.com (nos. 2002, 2004, 4240-4241, 4416, 6830).
• Muslim ibn al-Hajjaj. Sahih Muslim. English translation as published on sunnah.com (nos. 705b, 2408a).
• al-Tirmidhi, Muhammad ibn 'Isa. Jami' al-Tirmidhi. English translation as published on sunnah.com (no. 3713).
• Abu Dawud al-Sijistani. Sunan Abi Dawud. English translation as published on sunnah.com (no. 4284).

Orthodox and patristic sources

• This article draws on the site's own treatment of apostolic succession: the Apostolic Succession guide and Did the Early Church Believe in Apostolic Succession?, with the patristic sources cited there.

Other scholarship (including scholars who disagree)

• Ahmed, Shahab. "Hadith i. A General Introduction." Encyclopaedia Iranica XI/4 (2002): 442-47.
• "ʿAlī b. Abī Ṭāleb." Encyclopaedia Iranica I/8 (1985): 838-48.
• Arjomand, Saïd Amir. "Ḡayba." Encyclopaedia Iranica X/4 (2000): 341-44.
• Gause, F. Gregory, III. "Beyond Sectarianism: The New Middle East Cold War." Brookings Doha Center Analysis Paper. Washington, DC: Brookings Institution, 2014.
• Haider, Najam. Shi'i Islam: An Introduction. Cambridge: Cambridge University Press, 2014.
• Kazemi-Moussavi, Ahmad. "Hadith ii. Hadith in Shiʿism." Encyclopaedia Iranica XI/4-5 (2002): 447-49.
• Litvak, Meir. "Karbala." Encyclopaedia Iranica XV/5 (2010): 550-56.
• Madelung, Wilferd. The Succession to Muhammad: A Study of the Early Caliphate. Cambridge: Cambridge University Press, 1996 (Cambridge Core print date).
• Nanji, Azim. "Ismaʿilism xvii. The Imamate in Ismaʿilism." Encyclopaedia Iranica XIV/2 (2007): 210-12.
• Pew Research Center. Mapping the Global Muslim Population. Washington, DC, 2009.
• Pew Research Center. The World's Muslims: Unity and Diversity. Washington, DC, 2012.

Sources from the traditions discussed (Sunni and Shia)

• al-Tahawi, Abu Ja'far. al-'Aqida al-Tahawiyya. Translated by Iqbal Ahmad Azami. masud.co.uk.
• al-Muzaffar, Muhammad Ridha. The Faith of the Imamiyyah Shi'ah ('Aqa'id al-Imamiyyah). Translated by Badr Shahin. ABWA Publishing and Printing Center. al-islam.org.
• WikiShia (Ahl al-Bayt World Assembly). Articles "Adhan," "Combining Prayers," "Guardianship of the Jurist," "Qama-zani," "Turbah," "Zaydiyya." en.wikishia.net.
• The Amman Message (2004) and "The Three Points of the Amman Message" (2005). ammanmessage.com.