Shī‘a Islam, also Shi‘ite Islam or Shi‘ism (Arabic: شيعة; šīʿa), is the largest minority denomination (10-20%) based on the Islamic faith after Sunni Islam. Shias adhere to the teachings of Islamic prophet Muhammad and the religious guidance of his family (who are referred to as the Ahl al-Bayt) or his descendants known as Shi'a Imams, whom they consider to be infallible. Shia's assert the right of Ali ibn Abi Talib (Muhammad's cousin and husband of Fatimah) as successor to Muhammad, rejecting the legitimacy of the first three caliphs of Islamic history. The singular/adjective form is šīʿī (شيعي.) and refers to a follower of the faction of Ali according to the Shia ideology.