"I said: 'O Messenger of Allah, there is a man asking permission to enter your house.' The Messenger of Allah said: 'I think it is so-and-so the paternal uncle of Hafsah through breast-feeding.' 'Aishah said: If so-and-so (her own paternal uncle through breast-feeding) were alive, would he be allowed to enter upon me?' The Messenger of Allah said: 'What becomes unlawful (for marriage) through breast-feeding is that which becomes unlawful through birth.'" (Using translation from Nasāʾī 3313)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ عِنْدَهَا وَأَنَّهَا سَمِعَتْ صَوْتَ رَجُلٍ يَسْتَأْذِنُ فِي بَيْتِ حَفْصَةَ قَالَتْ عَائِشَةُ فَقُلْتُ يَا رَسُولَ اللهِ هَذَا رَجُلٌ يَسْتَأْذِنُ فِي بَيْتِكَ قَالَ رَسُولُ اللهِ ﷺ أُرَاهُ فُلَانًا لِعَمٍّ لِحَفْصَةَ مِنَ الرَّضَاعَةِ فَقَالَتْ عَائِشَةُ يَا رَسُولَ اللهِلَوْ كَانَ فُلَانٌ حَيًّا لِعَمِّهَا مِنَ الرَّضَاعَةِ دَخَلَ عَلَيَّ؟ فَقَالَ رَسُولُ اللهِ ﷺ نَعَمْ إِنَّ الرَّضَاعَةَ تُحَرِّمُ مَا تُحَرِّمُ الْوِلَادَةُ