It wasnarrated that Ibn 'Umar said:
"The Messenger of Allah (ﷺ)worea ring of silver, then he had engraved on it (the words)'MuhammadRasul Allah' (Muhammad the Messenger of Allah). And he said:'Noone should have his ring engraved like this ring of mine.'"
English reference: Vol. 4, Book 32, Hadith 3639
Arabic reference: Book 32, Hadith 3770