Ayesha reported,

Ayesha said, "My uncle through breastfeeding came and asked permission to enter. I refused to grant him permission until I had asked the Messenger of Allah ﷺ. When the Messenger of Allah ﷺ came, I asked him about it.He said, 'He is your uncle, so grant him permission.'I said, 'Messenger of Allah, it was the woman who breastfed me, not the man.'The Messenger of Allah ﷺ said, 'He is indeed your uncle, so let him enter upon you.'"Ayesha said, "This was after the verse of the veil had been revealed concerning us."Ayesha said, "Whatever is forbidden through birth is forbidden through breastfeeding."

Bukhari 5239

Sahih

حدثنا عبد الله بن يوسف أخبرنا مالك عن هشام بن عروة عن أبيه

عن عائشة رضي الله عنها أنها قالت

جاء عمي من الرضاعة فاستأذن علي فأبيت أن آذن له حتى أسأل رسول الله ﷺ فجاء رسول الله ﷺ فسألته عن ذلك فقال إنه عمك فأذني له قالت فقلت يا رسول الله إنما أرضعتني المرأة ولم يرضعني الرجل قالت فقال رسول الله ﷺ إنه عمك فليلج عليك قالت عائشة وذلك بعد أن ضرب علينا الحجاب قالت عائشة يحرم من الرضاعة ما يحرم من الولادة

البخاري 5239صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Marriage
Chapter
What is permissible of entering upon and looking at women through breastfeeding
Numbering
Darussalam 5239
Bukhari 5239