833 - وَ سَأَلَ اَلْحَسَنُ بْنُ مَحْبُوبٍ أَبَا اَلْحَسَنِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلْجِصِّ يُوقَدُ عَلَيْهِ بِالْعَذِرَةِ وَ عِظَامِ اَلْمَوْتَى ثُمَّ يُجَصَّصُ بِهِ اَلْمَسْجِدُ أَ يُسْجَدُ عَلَيْهِ فَكَتَبَ عَلَيْهِ اَلسَّلاَمُ إِلَيْهِ بِخَطِّهِ «أَنَّ اَلنَّارَ وَ اَلْمَاءَ قَدْ طَهَّرَاهُ.
Hadith.833 - Al-Hasan ibn Mahbub asked Imam Abu al-Hasan 
about gypsum (plaster) that was fired using dung and the bones of the dead, and whether it would be permissible to prostrate on it if a mosque was plastered with it.
The Imam wrote back in his own handwriting: "Fire and water have purified it”.
