Amr bin Shu'ayb narrates from his father, and he from his grandfather (Sayyiduna Abdullah bin Amr bin al-As, may Allah be pleased with them both), that "The Prophet (peace and blessings be upon him) forbade the gold ring and the iron ring."
No one narrated this hadith from Muhammad bin Ajlan (may Allah have mercy on him) except Hammam (may Allah have mercy on him).