From Sahih Bukhari (Hadith 5873):
Narrated Ibn `Umar:Allah's Messenger (ﷺ) 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 Messenger of Allah
Reference: Bukhari 5873