Hadith 2046
´It was narrated that Abu Hurairah said:` "The Messenger of Allah said: 'If any one of you were to sit on a live coal until it burns his garment, that would be better for him than sitting on a grave."
Hadith 2047
´It was narrated from 'Amr bin Hazm that the Messenger of Allah said:` "do not sit on graves."