The seventh Abbasid caliph (786–833 CE), who succeeded his father Hārūn al-Rashīd and ruled from 813 to 833 CE. He is known for his support of the Mu‘tazili interpretation of Muslim theology and for his ultimately unsuccessful attempt to impose it as the state policy. He encouraged the translation of scientific and philosophical works of other civilisations into Arabic at the Bayt al-Ḥikma (House of Wisdom), a centre he founded in Baghdad. With the aim of reconciling divisions between the Sunnis and Shi‘a, he appointed the Twelver Shi‘i Imam ʿAlī b. Mūsā al-Riḍā as his successor. But this attempt failed as ʿAlī died a year later and his followers accused al-Maʾmūn of having him poisoned.
