Shia traditional reports on the topic that Imams are twelve in number

H 112 - Informed me a group of scholar from Muhammad bin Yaqub from Ali Ashari from Husain bin Abdullah from Hasan from Musa Khashshab from Hasan bin Sama-a from Ali bin Hasan bin Rabat from Ibn Uzniyya from Zurarah that he said: I heard Imam Muhammad Baqir عليه السلام say: Twelve Imams from Aale Muhammad عليه السلام were all Muhaddath and they were from the descendants of the Messenger of Allah صلى الله عليه وعلى آله وسلم and Ali Ibn Abi Talib عليه السلام. Thus the Messenger of Allah صلى الله عليه وعلى آله وسلم and Imam Ali عليه السلام are their fathers.