Musnad Ahmad 435:45

Rawh narrated to us, Umar bin Sa’id bin Abi Husayn narrated to us, he said: Ali bin Abdullah narrated to me, that Ali bin Ali, a man from Banu Abd Shams, and Abdullah bin al-Harith, said: Umar bin Sa’id narrated to me, that Ali bin Abdullah bin Ali informed him, that his father informed him, that he said: I heard Mu’awiyah, upon the pulpit in Makkah, saying: "The Messenger of Allah, may Allah bless him and grant him peace, forbade the wearing of gold and silk."