Sunan an-Nasa'i, Volume 3, Book 21, Hadith 2046 (DarusSalam) ⓘ

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."

أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ الْمُبَارَكِ، عَنْ وَكِيعٍ، عَنْ سُفْيَانَ، عَنْ سُهَيْلٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ لأَنْ يَجْلِسَ أَحَدُكُمْ عَلَى جَمْرَةٍ حَتَّى تَحْرِقَ ثِيَابَهُ خَيْرٌ لَهُ مِنْ أَنْ يَجْلِسَ عَلَى قَبْرٍ ‏" ‏ ‏.‏