Examining the family relationship between Moses and Aaron and the importance of their descendants is essential for a better understanding of the Hebrew Bible and the Qurʾān and their intertextuality. A few modern scholars of the Hebrew Bible have brought to the surface the existence and importance of the Mushite priesthood in conjunction with the Aaronite priesthood during the biblical pre-monarchic and monarchic periods. In this paper, through a critical re-reading of the Hebrew Bible and a comparative study of the Hebrew Bible and the Qurʾān, I first propose that the biblical-qurʾānic Moses and Aaron are half-brothers with a matrilineal kinship. In the Hebrew Bible, although the two figures are called brothers, Moses, on one occasion, refers to Uzziel as the paternal uncle of Aaron (Lev 10:4) and not his own paternal uncle. Miriam is also called Aaron’s sister (Exod 15:20). Noteworthily, in the qurʾānic verse Q Ṭaha 20:94, Aaron calls Moses the “son of the mother” (ibn umm), although they are called brothers elsewhere in the Qurʾān. Based on these and other evidence, I suggest that while Miriam and Aaron are Jochebed’s children from her first marriage with Amram, Moses is the firstborn son from her second marriage with an unnamed Levite man. Secondly, through a comparative approach, I demonstrate that the text of the Qurʾān in Q al-Baqarah 2:248 equally emphasizes both Mushite and Aaronite lineages (ālu mūsā wa-ālu hārūn). This only saintly-priestly reference to them occurs in the context of the late biblical pre-monarchic period, within the story of the return of the Ark of Covenant as the sign of Saul’s kingship. I discuss that although ḥadīth literature is mainly silent about āl Mūsā, the exegetes of the Qurʾān have usually defined them as Moses himself, his followers, the Hebrew prophets, or his immediate family and not his descendants. Finally, I re-emphasize the existence of the Mushite and Aaronite schools of biblical writers and how their potential rivalry may have influenced the writing and canonizing of their ancestral stories. I also investigate the extent of knowledge about the Mushite and Aaronite priesthood in the sixth-century Judeo-Christian sources in the world of Late Antiquity. This study may shed light on the depth of scriptural intertextuality of the Bible and the Qurʾān and the characteristics of the qur’anic discourse with the People of the Book (ahl al-kitāb) on this subject.