Musnad Ahmad 5:417

Yazid narrated to us, Hisham informed us, from Muhammad, from Ubaydah, from Ali, who said: "He forbade the red silk saddle-cloths, the wearing of Qassi (silk-blend) garments, and the gold ring." Muhammad said: I mentioned that to my brother Yahya ibn Sirin, and he said: "Did you not hear this? Yes: 'And the silk trimmings.'"