Shi'a
Main article: Shi'a
See also: Succession to Muhammad
The Shi'a, who constitute the second-largest branch of Islam, believe in the political and religious leadership of Imams from the progeny of Ali ibn Abi Talib, who according to most Shi'a are in a state of ismah, meaning infallibility. They believe that Ali ibn Abi Talib, as the cousin and son-in-law of Muhammad, was his rightful successor, and they call him the first Imam (leader), rejecting the legitimacy of the previous Muslim caliphs. To most Shi'a, an Imam rules by right of divine appointment and holds "absolute spiritual authority" among Muslims, having final say in matters of doctrine and revelation.[140][141] Shi'a Islam has several branches, the largest of which is the Twelvers (iṯnāʿašariyya) which the label Shi'a generally refers to. Although the Twelver Shi'a share many core practices with the Sunni, the two branches disagree over the proper importance and validity of specific collections of hadith. The Twelver Shi'a follow a legal tradition called Ja'fari jurisprudence.[142] Other smaller groups include the Ismaili and Zaidi, who differ from Twelvers in both their line of successors and theological beliefs.[143]
