At-Tabarī
Muhammad ibn Jarir al-Tabari records that in A.H. 236 (850 –851) al-Muntasir led a pilgrimage. The previous year al-Mutawakkil had named his three sons as heirs and seemed to favour al-Muntasir. However, afterwards this seemed to change and al-Muntasir feared his father was going to move against him. So, he decided to strike first. Al-Mutawakkil was killed by a Turkish soldier on Wednesday 10 December 861.