Allah's Messenger, he is the person who seeks permission to enter your house, whereupon Allah's Messenger (ﷺ) said: I think he is so and so (uncle of Hafsa by reason of fosterage). 'A'isha said: Messenger of Allah, if so and so (her uncle by reason of fosterage) were alive, could he enter my house? Allah's Messenger (ﷺ) said: Yes. Fosterage makes unlawful what consanguinity makes unlawful.
Sahih Muslim Book 17, Hadith 1