Tafsir of Surah Al-Muddaththir 74:31
﴿وَمَا جَعَلْنَا أَصْحَابَ النَّارِ إِلَّا مَلَائِكَةً وَمَا جَعَلْنَا عِدَّتَهُمْ إِلَّا فِتْنَةً لِّلَّذِينَ كَفَرُوا لِيَسْتَيْقِنَ الَّذِينَ أُوتُوا الْكِتَابَ وَيَزْدَادَ الَّذِينَ آمَنُوا إِيمَانًا وَلَا يَرْتَابَ الَّذِينَ أُوتُوا الْكِتَابَ وَالْمُؤْمِنُونَ وَلِيَقُولَ الَّذِينَ فِي قُلُوبِهِم مَّرَضٌ وَالْكَافِرُونَ مَاذَا أَرَادَ اللَّهُ بِهَٰذَا مَثَلًا كَذَٰلِكَ يُضِلُّ اللَّهُ مَن يَشَاءُ وَيَهْدِي مَن يَشَاءُ وَمَا يَعْلَمُ جُنُودَ رَبِّكَ إِلَّا هُوَ وَمَا هِيَ إِلَّا ذِكْرَىٰ لِلْبَشَرِ﴾
Translation of the meaning
And We have not made the keepers of the Fire except angels. And We have not made their number except as a trial for those who disbelieve - that those who were given the Scripture will be convinced and those who have believed will increase in faith and those who were given the Scripture and the believers will not doubt and that those in whose hearts is disease [i.e., hypocrisy] and the disbelievers will say, "What does Allāh intend by this as an example?" Thus does Allāh send astray whom He wills and guide whom He wills. And none knows the soldiers of your Lord except Him. And it [i.e., mention of the Fire] is not but a reminder to humanity.
English Translation - Noor International Center — v1.1.2 · QuranEnc.comThe words of the two imams are given in their original Arabic, verbatim, with references.
Imam Ibn al-Qayyim
ومرض القلوب نوعان: مرض شبهة وشك، ومرض شهوة وغي، وكلاهما في القرآن.«زاد المعاد في هدي خير العباد» 4/5قال تعالى في مرض الشبهة: {في قلوبهم مرض فزادهم الله مرضا} [البقرة: 10] [البقرة: 10] وقال تعالى: {وليقول الذين في قلوبهم مرض والكافرون ماذا أراد الله بهذا مثلا} [المدثر: 31] [المدثر: 31]«زاد المعاد في هدي خير العباد» 4/5