Sahih Bukhari | Volume 7 | Hadith Number 762

Narrated by Ibn 'Umar
Allah's Apostle had a silver ring made for himself and it was worn by him on his hand. Afterwards it was worn by Abu Bakr, and then by 'Umar, and then by 'Uthman till it fell in the Aris well. (On that ring) was engraved: 'Muhammad, the Apostle of Allah."