Hazrat Ali (A.S.) was born in the Holy Kaaba at Mecca on Friday, the 13th day of Rajab, 600 A.D. Both the Holy Prophet and Hazrat Ali belonged to the same clan. They were Hashimites, the clan of Bani Hashim. Muhammad's father was Abdulla, and that of Hazrat Ali, Abu Talib. They were brothers and their father was Abdul Muttalib. Thus the Holy Prophet and Hazrat Ali were cousins. Hazrat Ali had two brothers, Ja'far and Aquil.
Hazrat Ali's mother Fatima was the daughter of Asad, a famous magnate of the Quraish clan. She was also the aunt of the Holy Prophet, being the wife of Abu Tabb, the Prophet's paternal uncle. When she was pregnant, she promised Muhammad to make over to him whatever child was born to her, be it male or female. Muhammad, aware of the issue that would be brought forth, gladly accepted the offer .