Sunan Abi Dawud, Hadith 3222

Narrated Abu Hurairah: The Messenger of Allah as saying: It is better that one of you should sit on the live coals which burns his clothing and come in contact with his skin than that he should sit on a grave.

حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا خَالِدٌ، حَدَّثَنَا سُهَيْلُ بْنُ أَبِي صَالِحٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ لأَنْ يَجْلِسَ أَحَدُكُمْ عَلَى جَمْرَةٍ فَتَحْرِقَ ثِيَابَهُ حَتَّى تَخْلُصَ إِلَى جِلْدِهِ خَيْرٌ لَهُ مِنْ أَنْ يَجْلِسَ عَلَى قَبْرٍ ‏" ‏ ‏.‏

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also referenced under: Hadith 3228 (DarusSalam)