until al-Amīn was killed and the people pledged allegiance to al-Maʾmūn at the beginning of 198 AH (1).

Al-Khaṭṭābī (2) said: “His kunya (teknonym) was Abū al-ʿAbbās; when he assumed the caliphate he adopted the kunya Abū Jaʿfar. His mother’s name was Marājil, and she died in the postpartum period after giving birth to him (3).”

He went on: “The caliphate was proclaimed for him toward the end of 195 AH, but it was only after al-Amīn was killed that the people united under him. He appointed al-Ḥasan ibn Sahl governor of Iraq, then secured the oath of succession for ʿAlī ibn Mūsā al-Riḍā, praised his name, abandoned the black banners and replaced them with green (4). The Abbasid clan thereupon rose in revolt, deposed al-Maʾmūn, and gave the oath of allegiance to his uncle Ibrāhīm ibn al-Mahdī (5), whom they styled al-Mubārak. They mustered their forces, and al-Ḥasan ibn Sahl fought them, but they routed him and he withdrew to Wāsiṭ. Al-Maʾmūn’s army—commanded by Ḥumayd al-Ṭūsī and ʿAlī ibn Hishām—then marched out, confronted Ibrāhīm, and defeated him. Ibrāhīm went into hiding for a time (6); nothing was heard of him until, eight years later, he was captured, whereupon al-Maʾmūn pardoned him (7).”

Al-Maʾmūn himself was learned, eloquent, and a powerful orator, and he used to say: “Muʿāwiyah ibn Abī—”