From Sahih Muslim (Hadith 5478):
Anas b. Malik reported that Allah's Apostle (ﷺ) had made for him a silver ring. and got engraved on it (Muhammad, Messenger of Allah) and said to the people I have got made a ring of silver and engraved in it (these words) (Muhammad, Messenger of Allah). So none should engrave these (words) like this engravement
Reference: Muslim 5478