Sunan Ibn Majah
3639
Sahih+3

It was narrated that Ibn ‘Umar said:“The Messenger of Allah (ﷺ) wore a ring of silver, then he had engraved on it (the words) ‘Muhammad Rasul Allah’ (Muhammad the Messenger of Allah). And he said: ‘No one should have his ring engraved like this ring of mine.’”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi