It was narrated that Anas bin Malik said: "The Messenger of Allah [SAW] put on a ring, and he had some words inscribed on it. He said: “We have put on a ring and have had some words engraved on it; no one of you should copy this inscription.'" Then Anas said: "It is as if I can see its whiteness on his hand”"
SahihSahihIsnaad SahihBook 48 · Hadith 169