Allah's Messenger (ﷺ) took a silver ring and had 'Muhammad, the Apostle' of Allah' engraved on it. The Prophet then said (to us), 'I have a silver ring with 'Muhammad, the Messenger of Allah engraved on it, so none of you should have the same engraving on his ring."
Sahih al-Bukhari Book 77, Hadith 94
← Previous Hadith The Prophet (ﷺ) had a golden ring made for himself, and when he wore it. he used to turn its stone toward the palm of his! hand. So the people too had gold made for themselves. The Prophet (ﷺ) then ascended the pulpit, and after glorifying and praising Allah, he said, "I had it made for me, but now I will never wear it again." He threw it away, and then the people threw away their rings too. (Juwairiya, a subnarrator, said: I think Anas said that the Prophet (ﷺ) was wearing the ring in his right hand.)

Sahih al-Bukhari Book 77, Hadith 93 Next Hadith → that when Abu Bakr became the Caliph, he wrote a letter to him (and stamped it with the Prophet's ring) and the engraving of the ring was in three lines: Muhammad in one line, 'Apostle' in another line, and 'Allah' in a third line.

Sahih al-Bukhari Book 77, Hadith 95