What did the inscription say that was engraved on the silver ring that was worn by Prophet Muhammad (saw)?
 Narrated 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."