Sahih Muslim Book 8, Hadith Number 3407.

Chapter: Kitab Al-Rada’a-Book pertaining to fosterage.

‘Ali (Allah be pleased with him) reported having said this: Messenger of Allah, why is it that you select (your wife) from among the Quraish, but you ignore us (the nearest of the kin)? Thereupon he said: Have you anything for me (a suitable match for me)? I said; Yes, the daughter of Hamza, whereupon Allah’s Messenger (May peace be upon him) said: She is not lawful for me, for she is the daughter of my brother by reason of fosterage.