Abu Bakr

Sunni Islam is the largest branch of Islam and the largest religious denomination in the world. It holds that Muhammad did not appoint any successor and that his closest companion Abu Bakr (r. 632–634) rightfully succeeded him as the caliph of the Muslim community, being appointed at the meeting of Saqifa. This contrasts with the Shia view, which holds that Muhammad appointed Ali ibn Abi Talib (r. 656–661) as his successor. Nevertheless, Sunnis revere Ali, along with Abu Bakr, Umar (r. 634–644) and Uthman (r. 644–656) as 'rightly-guided caliphs'.

The term Sunni means those who observe the sunna, the practices of Muhammad. The Quran, together with hadith (especially the Six Books) and ijma (scholarly consensus), form the basis of all traditional jurisprudence within Sunni Islam. Sharia legal rulings are derived from these basic sources, in conjunction with consideration of public welfare and juristic discretion, using the principles of jurisprudence developed by the four predominant legal schools: Hanafi, Maliki, Shafi'i and Hanbali.

Ali ibn Abi Talib (Arabic: عَلِيُّ بْن أَبِي طَالِب, romanized: ʿAlī ibn Abī Ṭālib) (c. 600 – 661 CE) was the fourth Rashidun caliph who ruled from 656 CE until his assassination in 661, as well as the first Shia Imam. He was the cousin and son-in-law of the Islamic prophet Muhammad. Born to Abu Talib ibn Abd al-Muttalib and Fatima bint Asad, Ali was raised by his elder cousin Muhammad and was among the first to accept his teachings.

Ali played a pivotal role in the early years of Islam when Muslims were severely persecuted in Mecca. After the immigration (hijra) to Medina in 622, Muhammad gave his daughter Fatima to Ali in marriage and swore a pact of brotherhood with him. Ali served as Muhammad's secretary and deputy in this period, and was the flag bearer of his army. Numerous sayings of Muhammad praise Ali, the most controversial of which was uttered in 632 at the Ghadir Khumm, "Whoever I am his mawla, then Ali is his mawla." The interpretation of the polysemous Arabic word mawla is disputed: For Shia Muslims, Muhammad thus invested Ali with his religious and political authority, while Sunni Muslims view this as a mere statement of friendship and rapport. When Muhammad died in the same year, a group of Muslims met in the absence of Ali and appointed Abu Bakr (r. 632–634) as their leader. Ali later relinquished his claims to leadership and resigned from public life during the reigns of Abu Bakr and his successor, Umar (r. 634–644). Even though his advice was occasionally sought, the conflicts between Ali and the first two caliphs are epitomized by his refusal to follow their practices. This refusal cost Ali the caliphate to the benefit of Uthman (r. 644–656), who was thus appointed to succeed Umar by the electoral council. Ali was also highly critical of Uthman, who was widely accused of nepotism and corruption. Yet Ali also repeatedly mediated between the caliph and the provincial dissidents angered by his policies.

The Saqifa (Arabic: سَقِيفَة, romanized: Saqīfah) of the Banu Sa'ida clan refers to the location of an event in early Islam where some of the companions of the Islamic prophet Muhammad pledged their allegiance to Abu Bakr as the first caliph and successor to Muhammad shortly after his death in 11 AH (632 CE). The Saqifa meeting is among the most controversial events in early Islam, due to the exclusion of a large number of Muhammad's companions, including his immediate family and notably Ali, his cousin and son-in-law. The conflicts that arose soon after Muhammad's death are considered to be the main cause of the current division among Muslims. Those who accepted Abu Bakr's caliphate were later labeled Sunnis, while the supporters of Ali's right to caliphate were later labeled Shia.

The Rashidun (Arabic: الراشدون, romanized: al-Rāshidūn, lit. 'the rightly-guided') are the first four caliphs (lit. 'successors') who led the Muslim community following the death of Muhammad: Abu Bakr (r. 632–634), Umar (r. 634–644), Uthman (r. 644–656), and Ali (r. 656–661).

The reign of these caliphs, called the Rashidun Caliphate (632–661), is considered in Sunni Islam to have been 'rightly guided' (Arabic: rāshid), meaning that it constitutes a model (Sunnah) to be followed and emulated from a religious point of view.

Fatima bint Muhammad (Arabic: فَاطِمَة بِنْت مُحَمَّد, romanized: Fāṭima bint Muḥammad; 605/15–632 CE), commonly known as Fatima al-Zahra' (Arabic: فَاطِمَة ٱلزَّهْرَاء, romanized: Fāṭima al-Zahrāʾ), was the daughter of the Islamic prophet Muhammad and his wife Khadija. Fatima's husband was Ali, the fourth of the Rashidun caliphs and the first Shia imam. Fatima's sons were Hasan and Husayn, the second and third Shia imams, respectively. Fatima has been compared to Mary, mother of Jesus, especially in Shia Islam. Muhammad is said to have regarded her as the best of women and the dearest person to him. She is often viewed as an ultimate archetype for Muslim women and an example of compassion, generosity, and enduring suffering. It is through Fatima that Muhammad's family line has survived to this date. Her name and her epithets remain popular choices for Muslim girls.

When Muhammad died in 632, Fatima and her husband Ali refused to acknowledge the authority of the first caliph, Abu Bakr. The couple and their supporters held that Ali was the rightful successor of Muhammad, possibly referring to his announcement at the Ghadir Khumm. Controversy surrounds Fatima's death within six months of Muhammad's. Sunni Islam holds that Fatima died from grief. In Shia Islam, however, Fatima's miscarriage and death are said to have been the direct result of her injuries during a raid on her house to subdue Ali, ordered by Abu Bakr. It is believed that Fatima's dying wish was that the caliph should not attend her funeral. She was buried secretly at night and her exact burial place remains uncertain.

Amr ibn al-As ibn Wa'il al-Sahmi (c. 585 – 664) was an Arab commander and companion of Muhammad who led the Muslim conquest of Egypt and served as its governor in 640–646 and 658–664. The son of a wealthy Qurayshite, Amr embraced Islam in c. 629 and was assigned important roles in the nascent Muslim community by the Islamic prophet Muhammad. The first caliph Abu Bakr (r. 632–634) appointed Amr as a commander of what became the conquest of Syria. He conquered most of Palestine, to which he was appointed governor, and helped lead the Arabs to decisive victories over the Byzantines at the battles of Ajnadayn and the Yarmuk in 634 and 636.

Amr launched the expedition that conquered Egypt on his own initiative in late 639, defeating the Byzantines in a string of victories ending with the surrender of Alexandria in 641 or 642. It was the swiftest of the early Muslim conquests. This was followed by westward advances by Amr as far as Tripoli in present-day Libya. In a treaty signed with the Byzantine governor Cyrus, Amr guaranteed the security of Egypt's population and imposed a poll tax on non-Muslim adult men. He maintained the Coptic-dominated bureaucracy and cordial ties with the Coptic patriarch Benjamin. He founded Fustat as the provincial capital with the mosque later called after him at its center. Amr ruled relatively independently, acquired significant wealth, and upheld the interests of the Arab conquerors who formed Fustat's garrison in relation to the central authorities in Medina. After gradually diluting Amr's authority, Caliph Uthman (r. 644–656) dismissed him in 646 after accusations of incompetence from his successor Abd Allah ibn Sa'd.

The Muslim conquest of the Levant (Arabic: فَتْحُ الشَّام, romanized: Fatḥ al-šām; lit. 'Conquest of Syria'), or Arab conquest of Syria, was a 634–638 CE conquest of Byzantine Syria by the Rashidun Caliphate.

A part of the wider Arab–Byzantine wars, the Levant was brought under Arab Muslim rule and developed into the provincial region of Bilad al-Sham. Clashes between the Arabs and Byzantines on the southern Levantine borders of the Byzantine Empire had occurred during the lifetime of Muhammad, with the Battle of Muʿtah in 629 CE. However, the actual conquest did not begin until 634, two years after Muhammad's death. It was led by the first two Rashidun caliphs who succeeded Muhammad: Abu Bakr and Umar ibn al-Khattab. During this time, Khalid ibn al-Walid was the most important leader of the Rashidun army.

Shia Islam is the second-largest branch of Islam. It holds that Muhammad designated Ali ibn Abi Talib (r. 656–661) as both his political successor (caliph) and as the spiritual leader of the Muslim community (imam). However, his right is understood to have been usurped by a number of Muhammad's companions at the meeting of Saqifa, during which they appointed Abu Bakr (r. 632–634) as caliph instead. As such, Sunni Muslims believe Abu Bakr, Umar (r. 634–644), Uthman (r. 644–656) and Ali to be 'rightly-guided caliphs', whereas Shia Muslims regard only Ali as the legitimate successor.

Shia Muslims believe that the imamate continued through Ali's sons, Hasan and Husayn, after which various Shia branches developed and recognized different imams. They revere the ahl al-bayt, the family of Muhammad, maintaining that they possess divine knowledge. Shia holy sites include the shrine of Ali in Najaf, the shrine of Husayn in Karbala, and other mausoleums of the ahl al-bayt. Later events, such as Husayn's martyrdom in the Battle of Karbala (680 CE), further influenced the development of Shia Islam, contributing to the formation of a distinct religious sect with its own rituals and shared collective memory.

From 613 to 619 CE, the Islamic prophet Muhammad gathered in his hometown of Mecca a small following of those who embraced his message of Islam and thus became Muslims. The first person who professed Islam was his wife, Khadija bint Khuwaylid. The identity of the second male Muslim, after Muhammad himself, is disputed largely along sectarian lines, as Shia and some Sunni sources identify him as the first Shia imam Ali ibn Abi Talib, a child at the time, who grew up in the household of his cousin, Muhammad. Other sources report that the first male convert was Abu Bakr, who later succeeded Muhammad as the first Sunni caliph, or Muhammad's foster son, Zayd ibn Haritha. While it is difficult to establish the chronological order of early conversions, the identities of early Muslims are known with some certainty.