Uncle and Foster Brother

Hamzah was a son of 'Abd al-Muttalib, chief of Banu Hashim, and so the Prophet's ﷺ uncle — but he was only a few years older than his nephew, and the two grew up almost as brothers. They were also brothers by nursing: Thuwaybah, a freedwoman of Abu Lahab, had nursed them both.

When it was later suggested to the Prophet ﷺ that he marry Hamzah's daughter, he declined, saying she was the daughter of his brother through nursing (Sahih al-Bukhari 2645). The tie of milk made Hamzah not only family but a brother.

Before Islam, Hamzah was known as a hunter and a man of strength and honour, respected by Quraysh and feared by those who crossed him.