Shia Islam

Shīʿa Islam, otherwise known as Shīʿism or as Shīʿite or Shīʿī Islam, is the second-largest branch of Islam. It holds that the Islamic prophet Muhammad designated ʿAlī ibn Abī Ṭālib as his successor and the Imam after him, most notably at the event of Ghadir Khumm, but was prevented from succeeding Muhammad as the leader of the Muslims as a result of the choice made by some of Muhammad's other companions at Saqifah. (Wikipedia)