Musnad Ahmad 27:1871

'Abd al-Razzaq narrated to us, Ma'mar informed us, from Ayyub, from Nafi', from Ibn 'Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) took a ring of gold, and he made its setting on the inside. He said: Then, while he was delivering a sermon one day, he said: "I had made a ring, and I used to wear it, and I would place its setting on the inside. And I, by Allah, will never wear it again." Then he cast it away, and the people cast away their rings.