Musnad Abu Ya'la al-Mawsili 3:343

Ubayd Allah ibn Umar narrated to us, Abu Amir al-Aqdi narrated to us, Dawud ibn Qays narrated to us, from Ibn Hunayn, from his father, from Ibn Abbas, from Ali, who said: The Messenger of Allah (may Allah bless him and grant him peace) forbade me from three things—I do not say he forbade the people: wearing gold rings, wearing silk-blend garments (al-qassi), and garments dyed with safflower (al-mu'asfar) that have been treated with a mordant (al-mufaddam), and that I recite [the Quran] while bowing or prostrating.