Musannaf Ibn Abi Shayba 16:908

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Yazid ibn Abi Ziyad, from Abu Sa’id, from Abu al-Kunud, who said: A great man among their great men was struck down on the day of Nahrawan, and a ring was found on him. I wore it, and Ali ibn Mas’ud saw it. He took it and placed it between two of his molars and broke it. Then he threw it to me and said: "Indeed, the Messenger of Allah (peace and blessings of Allah be upon him) forbade us from the gold ring."