The Reason for the Prohibition of Prostration on Food, Clothing, and Other Materials Except for Earth and What it Grows

قَالَ هِشَامُ بْنُ الْحَكَمِ‌[2]- لِأَبِي عَبْدِ اللَّهِ ع‌ أَخْبِرْنِي عَمَّا يَجُوزُ السُّجُودُ عَلَيْهِ وَ عَمَّا لَا يَجُوزُ قَالَ السُّجُودُ لَا يَجُوزُ إِلَّا عَلَى الْأَرْضِ أَوْ عَلَى مَا أَنْبَتَتِ الْأَرْضُ إِلَّا مَا أُكِلَ أَوْ لُبِسَ فَقَالَ لَهُ جُعِلْتُ فِدَاكَ مَا الْعِلَّةُ فِي ذَلِكَ قَالَ لِأَنَّ السُّجُودَ خُضُوعٌ لِلَّهِ عَزَّ وَ جَلَّ فَلَا يَنْبَغِي أَنْ يَكُونَ عَلَى مَا يُؤْكَلُ أَوْ يُلْبَسُ

Hadith.843 - Hisham ibn al-Hakam said to Imam Jafar ibn Muhammad Al-Sadiq (as): "Tell me about what is permissible to prostrate on and what is not." Imam (as) replied: "Prostration is only permissible on the earth or what grows from the earth, except for what is eaten or worn." Hisham then asked: "May I be your ransom,