Musannaf Ibn Abi Shayba 16:900

Abu Bakr narrated to us, he said: Ibn Numayr narrated to us, from Ubayd Allah, from Nafi’, from Ibn Umar, he said: The Messenger of Allah (peace and blessings of Allah be upon him) took a ring of silver. It was in his hand, then in the hand of Abu Bakr after him, then it was in the hand of Umar, then it was in the hand of Uthman, until it fell from him into the well of Aris. Its engraving was: "Muhammad, the Messenger of Allah."