الكافي 1/4/65/2

2. Muhammad ibn Yahya has narrated from Muhammad ibn al-Husayn and Ahmad ibn Muhammad from ibn Mahbub from Muhammad ibn Fudayl from abu Hamza al-Thumali who has said that he heard abu Ja‘far عليه السلام say the following. “When Muhammad صلى الله عليه وعلى آله وسلم completed his task of prophet-hood and the duration of his life was about to end Allah, the Most High sent him wahy information through the angels. It said, “O Muhammad, your task of prophet-hood has come to an end and the duration of your life is about to reach a close. Therefore, you must place the knowledge with you, the faith, the great name, the legacy of knowledge and the symbols of the knowledge of the prophet-hood in your family with Ali ibn abu Talib عليه السلام . It is because I do not want to discontinue the knowledge, the faith, the great name, the legacy of the of knowledge and the symbols of knowledge of the prophet-hood from your posterior descendents as I had not done so with descendents of the prophets.”