Mishkat al-Masabih 5 Funerals كتاب الجنائز 172

وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَأَنْ يَجْلِسَ أَحَدُكُمْ عَلَى جَمْرَةٍ فَتُحْرِقَ ثِيَابَهُ فَتَخْلُصَ إِلَى جِلْدِهِ خَيْرٌ لَهُ مِنْ أَنْ يجلس على قبر» . رَوَاهُ مُسلم

Abu Huraira reported God’s messenger as saying, “It is better that one of you should sit on live coals which burn his clothing and come in contact with his skin than that he should sit on a grave.” Muslim transmitted it.