Al-Kāfi
Hadith 155710ـ أَحْمَدُ بْنُ إِدْرِيسَ عَنْ مُحَمَّدِ بْنِ عَبْدِ الْجَبَّارِ قَالَ كَتَبْتُ إِلَى أَبِي مُحَمَّدٍ (عَلَيْهِ الْسَّلام) أَسْأَلُهُ هَلْ يُصَلَّى فِي قَلَنْسُوَةِ حَرِيرٍ مَحْضٍ أَوْ قَلَنْسُوَةِ دِيبَاجٍ فَكَتَبَ (عَلَيْهِ الْسَّلام) لاَ تَحِلُّ الصَّلاَةُ فِي حَرِيرٍ مَحْضٍ.
10. Ahmad ibn Idris has narrated from Muhammad ibn ‘Abd al-Jabbar who has said the following: “I once wrote to abu Muhammad (a.s.), asking if it is permissible to perform Salah (prayer) with a cap of pure silk or silk brocade. He (the Imam) wrote, ‘It is not lawful to perform Salah (prayer) with pure silk.’”