"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)
أَنَّهَا كَانَتْ مَعَ النَّبِيِّ ﷺ فِي بَيْتِ حَفْصَةَ فَسَمِعَتْ صَوْتَ إِنْسَانٍ قَالَتْ قُلْتُ يَا رَسُولَ اللَّهِ سَمِعْتُ صَوْتَ إِنْسَانٍ فِي بَيْتِكَ فَقَالَ رَسُولُ اللَّهِ ﷺ «أُرَاهُ فُلَانًا لِعَمِّ حَفْصَةَ مِنَ الرَّضَاعَةِ» قَالَتْ عَائِشَةُ يَا رَسُولَ اللَّهِ وَلَوْ كَانَ فُلَانٌ حَيًّا لِعَمِّهَا مِنَ الرَّضَاعَةِ دَخَلَ عَلَيَّ فَقَالَ رَسُولُ اللَّهِ ﷺ «نَعَمْ يَحْرُمُ مِنَ الرَّضَاعَةِ مَا يَحْرُمُ مِنَ الْوِلَادَةِ»