Narrated by Sayyida Aisha (may Allah be pleased with her), she says: The Noble Prophet (peace and blessings be upon him) came to me while a man was sitting with me. The face of the Prophet (peace and blessings be upon him) changed, as if he found this matter very unpleasant. I said: O Messenger of Allah! This is my foster brother. The Messenger of Allah (peace and blessings be upon him) said: Consider carefully who your brothers are; fosterage is established only by hunger (i.e., breastfeeding in infancy).