Sahih Muslim Book 24, Hadith Number 5215.

Chapter : Wearing of silver ring by Allah’s Apostle (may peace he upon him) in which were engraved the words (Muhammad the Messenger of Allah) and after him his successors wore it.

This hadith has been reported on the authority of Anas through another chain of transmitters but there is no mention of the words (Muhammad, Messenger of Allah)in it.