Muwatta Malik, Book 30, Hadith 1276 (In-Book) ⓘ

Yahya related to me from Malik from Hisham ibn Urwa from his father that A'isha, umm al-muminin said, "My paternal uncle by suckling came to me and I refused to give him permission to enter until I had asked the Messenger of Allah, may Allah bless him and grant him peace, about it. The Messenger of Allah, may Allah bless him and grant him peace, came and I asked him about it. He said, 'He is your paternal uncle, so give him permission.' So I said, 'Messenger of Allah! The woman nursed me not the man.' He said, 'He is your paternal uncle, so let him enter.' " A'isha said, "That was after the veil had been imposed on us." A'isha added, "What is haram by birth is made haram by suckling."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ أُمِّ الْمُؤْمِنِينَ، أَنَّهَا قَالَتْ جَاءَ عَمِّي مِنَ الرَّضَاعَةِ يَسْتَأْذِنُ عَلَىَّ فَأَبَيْتُ أَنْ آذَنَ لَهُ عَلَىَّ حَتَّى أَسْأَلَ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ ذَلِكَ فَجَاءَ رَسُولُ اللَّهِ صلى الله عليه وسلم فَسَأَلْتُهُ عَنْ ذَلِكَ فَقَالَ ‏"‏ إِنَّهُ عَمُّكِ فَأْذَنِي لَهُ ‏"‏ ‏.‏ قَالَتْ فَقُلْتُ يَا رَسُولَ اللَّهِ إِنَّمَا أَرْضَعَتْنِي الْمَرْأَةُ وَلَمْ يُرْضِعْنِي الرَّجُلُ ‏.‏ فَقَالَ ‏"‏ إِنَّهُ عَمُّكِ فَلْيَلِجْ عَلَيْكِ ‏"‏ ‏.‏ قَالَتْ عَائِشَةُ وَذَلِكَ بَعْدَ مَا ضُرِبَ عَلَيْنَا الْحِجَابُ ‏.‏ وَقَالَتْ عَائِشَةُ يَحْرُمُ مِنَ الرَّضَاعَةِ مَا يَحْرُمُ مِنَ الْوِلاَدَةِ ‏.‏