Musnad Abu Ya'la al-Mawsili 3:43

Ubayd Allah ibn Umar narrated to us, Yahya narrated to us, from Fitr, from Mundhir Abu Ya'la, from Muhammad ibn al-Hanafiyyah, from Ali, that he asked the Messenger of Allah (peace and blessings of Allah be upon him) for permission: if a child were born to him after him, could he name him with his name and give him his kunyah (patronymic) with his kunyah? He said: So it was a concession from the Messenger of Allah (peace and blessings of Allah be upon him). He said: And his name was Muhammad, and his kunyah was Abu al-Qasim.