It is narrated from Hazrat Aisha (may Allah be pleased with her) that once the Prophet (peace and blessings be upon him) was sitting with her when a man's voice was heard, who was seeking permission to enter the house of Hazrat Hafsa (may Allah be pleased with her). I said, "O Messenger of Allah! This man is seeking permission to enter your house." The Prophet (peace and blessings be upon him) said, "I think it is such-and-such a man." The Prophet (peace and blessings be upon him) was referring to the foster uncle of Hazrat Hafsa (may Allah be pleased with her). I said, "O Messenger of Allah (peace and blessings be upon him)! If such-and-such a man, that is, my foster uncle, were alive, could he also come to me?" The Prophet (peace and blessings be upon him) said, "Yes! Because all those relationships become prohibited due to fosterage which become prohibited due to lineage."