Musnad Ahmad 5:549

Abdullah narrated to us, Ishaq bin Isma'il narrated to us, Yahya bin 'Abbad narrated to us, Shu'bah narrated to us, Abu Ishaq informed me, from Hubayrah, from 'Ali, who said: "The Messenger of Allah (ﷺ) forbade the gold ring, the wearing of *al-qassi* (a type of silk garment), and the *maytharah* (a saddlecloth made of silk or animal fur)."