(7) باب الشَّهَادَةِ عَلَى الأَنْسَابِ وَالرَّضَاعِ الْمُسْتَفِيضِ وَالْمَوْتِ الْقَدِيمِ
Narrated Ibn `Abbas:
The Prophet (ﷺ) said about Hamza's daughter, "I am not legally permitted to marry her, as foster relations are treated like blood relations (in marital affairs). She is the daughter of my foster brother."
Reference: Sahih al-Bukhari 2645
In-book reference: Book 52, Hadith 9
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 48, Hadith 813