Sunan an-Nasa'i 5195

Abdullah bin Buraidah narrated from his father that:A man came to the Prophet [SAW] and he was wearing an iron ring. He said: "Why do I see you wearing the jewelry of the people of Hell?" He threw it away, then he came and he was wearing a brass ring. He said: "Why do I notice the stench of idols from you?" So he threw it away, and said: "O Messenger of Allah, what should I use?" He said: "Silver, but it should not equal a Mithqal