The Prophet ﷺ had a ring made of gold, then he discarded it. He then had a ring made of silver, with the inscription "Muhammad, Messenger of Allah" engraved upon it. He said, "No one is to engrave anything resembling the inscription of this ring of mine."Whenever he wore it, he would turn the stone toward the inside of his palm. This is the very ring that fell from Muqayqib into the well of Aris.
اتخذ النبي ﷺ خاتما من ذهب، ثم ألقاه، ثم اتخذ خاتما من ورق ونقش فيه: محمد رسول الله، وقال: لا ينقش أحد على نقش خاتمي هذا، وكان إذا لبسه جعل فصه مما يلي بطن كفه، وهو الذي سقط من معيقيب في بئر أريس.
Muslim narrated it in the Book of Clothing (2091:55) through several routes, from Sufyan bin Uyayna, from Ayub bin Musa, from Nafi, from Ibn Umar, who related it.As for his saying, "No one should engrave the same engraving as my ring," this was because he ﷺ used to write to kings, chiefs, and others and seal his letters with it. So if someone else engraved a ring like his during his ﷺ lifetime, it would have led to harm, unlike the caliphs who came after him.