Musnad Ahmad 5:160

'Affan narrated to us, Shu'bah narrated to us, he said: Abu Ishaq informed us, he said: I heard Hubayrah saying: I heard 'Ali saying: "The Messenger of Allah (may Allah bless him and grant him peace) forbade me—or the Messenger of Allah (may Allah bless him and grant him peace) forbade me—from the gold ring, the Qassi (garment containing silk), and the Maytharah (a saddlecloth made of silk or animal fur)."