Most Muslims believe that Muhammad was the last prophet, who brought the final scripture (the Qur'an) to humanity. Shi'as believe that, after his death, God appointed 12 infallible Imams to guide the Muslim community, leading them on the path set by the Prophet Muhammad. These Imams are part of what Shi'as call Ahl al-Bayt (the Family of the House). In other words, they are part of Prophet Muhammad's extended household. Of these 12, 11 have been killed. They believe that the 12th (or hidden) Imam is still alive, but is in hiding (occultation), waiting to reappear and rule on earth with justice. They sometimes refer to him as the Mahdi.