Musnad Ahmad 5:268

Abdullah narrated to us, Muhammad ibn Ubayd ibn Muhammad al-Muharibi narrated to me, Abdullah ibn al-Ajlah narrated to us, from Ibn Abi Layla, from Abd al-Karim, from Abdullah ibn al-Harith, from Ibn Abbas, from Ali, who said: "The Messenger of Allah, may Allah bless him and grant him peace, forbade me from wearing *al-qassi* (silk-blend garments), *al-mayathir* (silk saddle cushions), and *al-mu'asfar* (garments dyed with safflower), and from reciting the Quran while a man is bowing or prostrating."