According to scholars, he was of Arab or Persian origin. The "nisbah" of "al-Qushayri" signifies Muslim's belonging to the Arab tribe of Banu Qushayr, members of which migrated to the newly conquered Persian territory during the expansion of the Rashidun Caliphate. A scholar named Shams al-Dīn al-Dhahabī introduced the idea that he may have been a "mawla" of Persian descent, attributed to the Qushayr tribe by way of "wala"' (alliance). An ancestor of Muslim may have been a freed slave of a Qushayri, or may have accepted Islam at the hands of a Qushayri. According to two other scholars, Ibn al-Athīr and Ibn al-Salāh, he was actually an Arab member of that tribe of which his family had migrated to Iran nearly two centuries earlier following the conquest.