Musnad Abu Ya'la al-Mawsili 3:65

Ubayd Allah narrated to us, Yazid ibn Harun narrated to us, Muhammad ibn Ishaq informed us, from Yazid ibn Abi Habib, from Abd al-Aziz ibn Abi al-Sa'bah, from Abu Aflah al-Hamdani, from Abdullah ibn Zurayr al-Ghafiqi, who said: I heard Ali saying: The Messenger of Allah, may Allah bless him and grant him peace, took gold in his right hand and silk in his left hand, and said: "These two are forbidden for the males of my nation."