Imam as-Sadiq (a) narrated that one of the Prophet’s foster sisters visited him. He received her so warmly, laid his personal quilt, asked her to sit on it, and went on facing her and smiling in her face. When she left, her brother came. The Prophet (s) did not treat him as same as his sister. When the man left, the attendants asked him why he had treated the woman so warmly, but had not done the same with her brother. He answered: “She was more obedient to her parents than he was.”( al-Wafi; part 3 page 92 (as quoted from al-Kafi) )