Although Muḥammad had no natural sons who reached the age of maturity, Islamic sources report that he adopted a man named Zayd shortly before receiving his first revelation. This "son of Muḥammad" was the Prophet's heir for the next fifteen or twenty years. He was the first adult male to become a Muslim and the only Muslim apart from Muḥammad whose name is mentioned in the Qur'an. Eventually, Muḥammad would repudiate Zayd...