Imāmah (Arabic: إِمَامَة) means "leadership" and is a concept in Twelver theology. The Twelve Imams are the spiritual and political successors to Muhammad, the Prophet of Islam, in the Twelver branch of Shia Islam. According to Twelver theology, the successors to Muhammad are infallible human beings, who rule justly over the community and maintain and interpret sharia and undertake the esoteric interpretation of the Quran. The words and deeds of Muhammad and the Imams guide the community. For this, the Imams must be free from error and sin and chosen by divine decree—nass—through the Prophet.