From Sahih Muslim (Hadith 3568):
A'isha (Allah be pleased with her) reported tha Allah's Messenger (ﷺ) was with her and she heard the voice of a person seeking permission to enter the house of Hafsa. 'A'isha (Allah he pleased with her) said: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
Reference: Muslim 3568