It is narrated from Sayyiduna Umar (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) saw a man wearing a gold ring on his hand. The Prophet (peace and blessings be upon him) said: "Remove it." So he removed it and wore an iron ring in its place. The Prophet (peace and blessings be upon him) said: "This is even worse than that." Then he wore a silver ring, and the Prophet (peace and blessings be upon him) remained silent about it.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 132
Hadith Gradingحکم دارالسلام:حسن لغيره، وهذا إسناد ضعيف لانقطاعه، عمار بن أبى عمار لم يدرك عمر