In 786 Musa was one of the Abbasid commanders who successfully put down a pro-Alid rebellion in Mecca at the Battle of Fakhkh, with he and al-Abbas ibn Muhammad ibn Ali leading the left wing of the army during the fighting. Despite having played a prominent role in the victory, he afterwards received criticism for his decision to execute al-Hasan ibn Muhammad, a son of Muhammad al-Nafs al-Zakiyya who had participated in the revolt. As punishment for failing to keep al-Hasan alive for judgement, the caliph al-Hadi (r. 785–786) ordered that Musa's goods and properties be confiscated, and they remained under sequestration until al-Hadi's death later that year.[9]