Hazrat Hammaad bin Salamah says that he saw Hazrat Abdur Rahman bin Abi Rafe' wearing a ring on his right hand. He asked him the reason and he replied, "I had seen Hazrat Abdullah bin Ja'far radiyallahu anhu wearing a ring on his right hand, and he said that he had seen the Prophet of Allah sallallahu alaihe wasallam wear a ring on the right hand." (RU)
English reference (RU): Book 12, Hadith 91 (RU)
Arabic reference (RU): Book 13, Hadith 97 (RU)