(21) بَابُ مَنْ قَالَ لاَ رَضَاعَ بَعْدَ حَوْلَيْنِ
Narrated `Aisha:
that the Prophet (ﷺ) entered upon her while a man was sitting with her. Signs of answer seemed to appear on his face as if he disliked that. She said, "Here is my (foster) brother." He said, "Be sure as to who is your foster brother, for foster suckling relationship is established only when milk is the only food of the child."
Reference: Sahih al-Bukhari 5102
In-book reference: Book 67, Hadith 40
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 7, Book 62, Hadith 39