Sunan Ibn Majah
3641
Sahih+3

It was narrated from Anas bin Malik that the Messenger of Allah (ﷺ) wore a ring of silver, in which was an Ethiopian gemstone and the inscription:‘Muhammad Rasul Allah’ (Muhammad the Messenger of Allah).”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi