It is narrated from Hazrat Aisha (may Allah be pleased with her) that once the Prophet (peace and blessings be upon him) came to her place and there was a man present there. The Prophet (peace and blessings be upon him) asked, "Who is this?" She replied, "O Messenger of Allah! This is my foster brother." The Prophet (peace and blessings be upon him) said, "Make sure to verify who your brothers are, for the relationship of fosterage is established only through hunger (that is, within two and a half years, during which the child's hunger is satisfied only by that milk)."