Ali (ˈɑːli,_ɑːˈliː; علي, ʕaliː; 13 Rajab, 21 BH – 21 Ramadan, 40 AH (c. 594 – 29 January 661) was the cousin and son-in-law of Muhammad, the prophet of Islam. He ruled as the fourth caliph from 656 to 661, and was first Imam of Shia Islam from 632 to 661. Born to Abu Talib and Fatimah bint Asad, Ali was the only child believed to have been born in the sacred sanctuary of the Ka‘bah (كَـعـبَـة) in Mecca, the holiest place in Islam, according to many classical Islamic sources, especially Shia ones. Ali was the first young male who accepted Islam. After migrating to Medina, he married Muhammad's daughter Fatimah. Ali took part in the early caravan raids from Mecca and later in almost all the battles fought by the nascent Muslim community. He was appointed caliph by Muhammad's Companions (Sahaba) in 656, after Caliph Uthman ibn Affan was assassinated. Ali's reign saw civil wars and in 661, he was attacked and assassinated by a Kharijite while praying in the Great Mosque of Kufa, dying two days later. Ali is important to both Sunni and Shi'ite denominations, politically and spiritually. The numerous biographical sources about Ali are often biased according to sectarian lines, but they agree that he was a pious Muslim, devoted to the cause of Islam and a just ruler in accordance with the Qur'an and the Sunnah. While Sunnis consider Ali the fourth and final of the Rashidun (rightly guided) caliphs, Shi'ites regard Ali as the first Imam after Muhammad due to their interpretation of the events at Ghadir Khumm. Shias also believe that Ali and the other Shi'ite Imams (all of whom are members of the Bayṫ (بَـيـت, Household) of Muhammad) are the rightful successors to Muhammad. This disagreement split the Ummah (أُمَّـة, Muslim Community) into the Sunni and Shia branches.
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