Sahih Bukhari Volume 007, Book 072, Hadith Number 756.
Narrated By Ibn. 'Umar : Allah's Apostle wore a gold ring or a silver ring and placed its stone towards the palm of his hand and had the name 'Muhammad, the Apostle of Allah' engraved on it. The people also started wearing gold rings like it, but when the Prophet saw them wearing such rings, he threw away his own ring and said. "I will never wear it," and then wore a silver ring, whereupon the people too started wearing silver rings. Ibn Umar added: After the Prophet Abu Bakr wore the ring, and then Umar and then 'Uthman wore it till it fell in the Aris well from 'Uthman. bin 'Umar : Allah's Apostle wore a gold ring, then he threw it and said, "I will never wear it." The people also threw their (gold) rings.