Musnad Ahmad 27:287

Ibn Numayr narrated to us, Ubaydullah narrated to us, from Nafi’, from Ibn Umar, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) took a ring of silver, and it was on his hand." Then it was on the hand of Abu Bakr after him, then it was on the hand of Umar, then it was on the hand of Uthman. Its inscription was: "Muhammad the Messenger of Allah."