My uncle through breastfeeding came seeking permission to enter, but I refused to admit him. The Messenger of Allah ﷺ said, "Let your uncle come in to you."I said, "It was the woman who nursed me, not the man."He replied, "He is your uncle, so let him come in to you."
حدثنا أبو بكر بن أبي شيبة حدثنا عبد الله بن نمير عن هشام بن عروة عن أبيه
جاء عمي من الرضاعة يستأذن علي فأبيت أن آذن له فقال رسول الله ﷺ فليلج عليك عمك فقلت إنما أرضعتني المرأة ولم يرضعني الرجل قال إنه عمك فليلج عليك
Muslim narrated it in the Book of Breastfeeding, Chapter on the Prohibition of Breastfeeding Through the Milk of the Husband, no. 1445/7, from Ibn Abu Shayba and others, with this wording. Bukhari also narrated it in the Book of Marriage, Chapter on What Is Permissible Regarding Entering and Looking at Women in Cases of Breastfeeding, no. 5239, through the route of Malik, from Hisham, with this wording, in a similar but longer form.