Hadith 8:158
Abu Musa reported the Prophet as saying, “The greatest sin in God's sight, after the serious sins which God has prohibited, which a man can bring into His presence is that he should die in debt without leaving enough to discharge it.” Ahmad and Abu Dawud transmitted it.
وَعَنْ أَبِي مُوسَى عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «إِنَّ أَعْظَمَ الذُّنُوبِ عِنْدَ اللَّهِ أَنْ يَلْقَاهُ بِهَا عَبْدٌ بَعْدَ الْكَبَائِرِ الَّتِي نَهَى اللَّهُ عَنْهَا أَنْ يَمُوتَ رَجُلٌ وَعَلَيْهِ دَيْنٌ لَا يَدَعُ لَهُ قَضَاءً» . رَوَاهُ أَحْمد وَأَبُو دَاوُد
Original Reference: Mishkat al-Masabih 2922