Musnad Ahmad 27:1647

'Affan narrated to us, Abu 'Awanah narrated to us, from Abu Bishr, from Nafi', from Ibn 'Umar, who said: "The Prophet, peace and blessings of Allah be upon him, had a ring of gold, and he used to place its stone on the inside of his palm. Then he cast it away one day, so the people cast away their rings. Then he took a ring of silver, and he used to stamp with it, and he would not wear it."