الكافي 2/1/69/12

12. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad ibn ‘Isa from Ali ibn al-Hakam a number of our people from Ahmad ibn abu ‘Abd Allah from Isma’il ibn Mehran all from Sayf ibn ‘ Amirah from ‘Abd Allah ibn Muskan from ‘Ammar ibn Hayyan who has said the following: “Once I explained to Abu ‘Abdillah عليه السلام how kind my son Isma’il was to me. The Imam said, ‘I loved him before and this has increased my love for him. Once, the sister of the Messenger of Allah (through breast-feeding) visited him. When he saw her he became very happy to see her, prepared a seat for her, began to talk to her and smiled at her. She left and her brother came. The Holy Prophet did not behave toward him as he did to her. He was asked, ‘O Messenger of Allah, you behaved toward his sister differently from the way you behaved toward him, and he is a man.’ The Messenger of Allah said, ‘It was because she was more kind to her parents than he was.’”