Musnad Ahmad 5:188

Yazid narrated to us, Muhammad ibn Ishaq informed us, from Yazid ibn Abi Habib, from Abd al-Aziz ibn Abi al-Sa'bah, from Abdullah ibn Zurayr al-Ghafiqi, who said: I heard Ali saying: The Messenger of Allah, peace and blessings of Allah be upon him, took gold in his right hand and silk in his left hand. Then he raised his hands with them and said: "These two are forbidden for the males of my nation."