Ali bin Abi Talib was the first cousin of the Prophet. Moreover, he had grown up in the Prophet's own household, later marrying his youngest daughter, Fatima, and never ceased to support the prophetic call throughout his life.

Ali was ten years old when the divine message came to Muhammad. One night he saw the Prophet and his wife Khadijah bowing and prostrating. He asked the Prophet about the meaning of their actions. The Prophet told him that they were praying to God Most High and that Ali too should accept Islam. Ali said that he would first like to ask his father about it. He spent a sleepless night, and in the morning he went to the Prophet and said, "When God created me He did not consult my father, so why should I consult my father in order to serve God?" and he accepted the truth of Muhammad's message.

Ibn Taymiyya once said that Ali was the best of the Ahl al-Bayt (the Prophet's house-hold) and the best of Bani Hashim after the Prophet.