12. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from Muhammad ibn Khalid from ’Isma‘il ibn Sa‘d al-Ahwas who has said the following: “I once asked abu al-Hassan al-Rida’ عليه السلام, about performing Salah (prayer) with the skin of beasts. He (the Imam) said, ‘Do not perform Salah (prayer) with it.’ He (the narrator) has said that he then asked him (the Imam) about performing Salah (prayer) with Abrisam (silk). He (the Imam) said, ‘No, it is not permissible.’”