(the wife of the Prophet) that while Messenger of Allah ﷺ was with her, she heard a voice of a man asking permission to enter the house of Hafsa. ʿAisha added: I said, "O Messenger of Allah ﷺ! This man is asking permission to enter your house." The Prophet ﷺ said, "I think he is so-and-so," naming the foster-uncle of Hafsa. ʿAisha said, "If so-and-so," naming her foster uncle, "were living, could he enter upon me?" The Prophet ﷺ said, "Yes, for foster suckling relations make all those things unlawful which are unlawful through corresponding birth (blood) relations." (Using translation from Bukhārī 5099)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ عِنْدَهَا وَأَنَّهَا سَمِعَتْ صَوْتَ رَجُلٍ يَسْتَأْذِنُ فِي بَيْتِ حَفْصَةَ فَقَالَتْ عَائِشَةُ فَقُلْتُ يَا رَسُولَ اللهِ هَذَا رَجُلٌ يَسْتَأْذِنُ فِي بَيْتِكَ فَقَالَ رَسُولُ اللهِ ﷺ «أَرَاهُ فُلَانًا لِعَمِّ حَفْصَةَ مِنَ الرَّضَاعَةِ» قَالَتْ عَائِشَةُ فَقُلْتُ يَا رَسُولَ اللهِ لَوْ كَانَ فُلَانٌ حَيًّا لِعَمِّهَا مِنَ الرَّضَاعَةِ دَخَلَ عَلَيَّ فَقَالَ رَسُولُ اللهِ ﷺ «إِنَّ الرَّضَاعَةَ تُحَرِّمُ مَا تُحَرِّمُ الْوِلَادَةُ»