Muhammad’s earliest and most authoritative biography traces his lineage back to Abraham though Ishmael. This way, Muhammad, like Moses and Jesus, is connected to the great patriarch Abraham. Muslims identify Ishmael as the father of many Arab tribes, and claim that he was definitely the ancestor of the Arabian prophet, Muhammad. This is why Muslims identify as “the Sons of Ishmael,” especially because Ishmael is revered in the Quran as a prophet of Allah (Q 19:54) and is mentioned explicitly twelve times, even more than Muhammad. With this identification of Muhammad as tracing back to Abraham through Ishmael, many claim that Muhammad’s religion, Islam, is an Abrahamic religion which came from the same source as Judaism and Christianity. However, based on historical accounts and even some Muslim reports, this claim is just that. In this paper, I begin by tracing the traditions surrounding Abraham and Ishmael as ancestors of Muhammad who built the Ka’ba in Mecca. I then highlight why it is significant for Muslims to insist that Muhammad’s lineage traces back to Abraham, and that he and his son Ishmael were present at Mecca at some point in history. This is followed by examining and analyzing conflicting historical traditions—from the classical Muslim accounts themselves—that present a completely contradicting picture, indicating that Muhammad’s lineage had nothing to do with Ishmael, thus shedding doubt on the traditional claim as whole. Finally, as I question the veracity of the Muslim claim linking Muhammad to Abraham, I examine recent scholarly research that questions the plausibility of tracing Muhammad to Abraham. I conclude with explaining (1) when the Muslim claim might have emerged, (2) reasons for its emergence, and (3) how it is reemphasized in contemporary discourse on Islam as an Abrahamic religion. I will conclude with observations related to evangelism among Muslims and how one can engage the Islamic claim that Muslims are the sons of Ishmael.