Under the succession arrangements made by al-Saffah in 754, Musa's father Isa was originally the designated second heir-apparent to the caliphate after al-Saffah's brother al-Mansur; in 764/5, however, Isa was pressured by al-Mansur into yielding his rights and recognizing the caliph's son al-Mahdi's claims to the throne ahead of his own. According to some versions of this event, Musa feared that al-Mansur would have his father killed if he refused to step aside; he therefore worked together with the caliph and helped to convince Isa to withdraw from the succession.[5]