وَ سَأَلَ الْحَسَنُ بْنُ مَحْبُوبٍ أَبَا الْحَسَنِ ع- عَنِ الْجِصِّ يُوقَدُ عَلَيْهِ بِالْعَذِرَةِ وَ عِظَامِ الْمَوْتَى ثُمَّ يُجَصَّصُ بِهِ الْمَسْجِدُ أَ يُسْجَدُ عَلَيْهِ فَكَتَبَ ع إِلَيْهِ بِخَطِّهِ أَنَّ النَّارَ وَ الْمَاءَ قَدْ طَهَّرَاهُ[1].
Hadith.833 - Al-Hasan ibn Mahbub asked Imam Abu al-Hasan (as) 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”.