`Aisha, the wife of the Prophet (ﷺ) told her that once Allah's Messenger (ﷺ) was with her and she heard
somebody asking permission to enter Hafsa's house. She said, "O Allah's Messenger (ﷺ)! This man is asking
permission to enter your house." Allah's Messenger (ﷺ) replied, "I think he is so-and-so (meaning the foster
uncle of Hafsa). What is rendered illegal because of blood relations, is also rendered illegal because of
the corresponding foster-relations."
Sahih al-Bukhari Book 57, Hadith 14