“Once Ali ibn Bilal wrote to abu al-Hassan (a.s.), about the condition of a grave asking, ‘Someone may die in our area but the ground of the grave is wet.’ We pave it (the floor) with teak (wooden board) or cover it in this way, is this permissible? He (the Imam) wrote the answer, ‘It is permissible.’” H 4536, Ch. 64, h 2