Musannaf Ibn Abi Shayba 36:548

Ibn Idris narrated to us, from Hisham, from Ibn Sirin, who said: Zayd ibn Thabit came to Uthman. He said: "These Ansar are at the door. They say: 'If you wish, we will be the Ansar of Allah twice.'" He said: "As for fighting, then no."