Muhammad ibn Ahmad ibn Yahya, from Mu‘awiyah ibn Hakim, from Mu‘ammar ibn Khallad, who said:
I asked Abu al-Hasan al-Ridha عليه السلام, peace be upon him, about prayer in khazz (a type of fine fabric). Imam عليه السلام said: "Pray in it."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 225