Hazrat Ibn Umar radiyallahu anhu relates that the Prophet of Allah sallallahu alaihe wasallam had a ring made of gold which he wore on his right hand. The Sahabah radiyallahu anhum in imitating the Prophet of Allah sallallahu alaihe wasallam also had gold rings made for themselves. Thereafter, the Prophet of Allah sallallah alaihe wasallam threw away the gold ring and said, "I will never wear it again."
English reference: Book 12, Hadith 98
Arabic reference: Book 13, Hadith 104