Hardness of heart (Qaswah) in the Holy Quran

﴿ثُمَّ قَسَتۡ قُلُوبُكُم مِّنۢ بَعۡدِ ذَٰلِكَ فَهِيَ كَٱلۡحِجَارَةِ أَوۡ أَشَدُّ قَسۡوَةٗۚ وَإِنَّ مِنَ ٱلۡحِجَارَةِ لَمَا يَتَفَجَّرُ مِنۡهُ ٱلۡأَنۡهَٰرُۚ وَإِنَّ مِنۡهَا لَمَا يَشَّقَّقُ فَيَخۡرُجُ مِنۡهُ ٱلۡمَآءُۚ وَإِنَّ مِنۡهَا لَمَا يَهۡبِطُ مِنۡ خَشۡيَةِ ٱللَّهِۗ وَمَا ٱللَّهُ بِغَٰفِلٍ عَمَّا تَعۡمَلُونَ ﴾ [Al-Baqarah: 74]

(74) Then your hearts became hardened after that, being like stones or even harder. For indeed, there are stones from which rivers burst forth, and there are some of them that split open and water comes out, and there are some of them that fall down for fear of Allah. And Allah is not unaware of what you do.

Surah: Al-Baqarah - Verse: 74 - Juz: 1 - Page: 11

﴿فَبِمَا نَقۡضِهِم مِّيثَٰقَهُمۡ لَعَنَّٰهُمۡ وَجَعَلۡنَا قُلُوبَهُمۡ قَٰسِيَةٗۖ يُحَرِّفُونَ ٱلۡكَلِمَ عَن مَّوَاضِعِهِۦ وَنَسُواْ حَظّٗا مِّمَّا ذُكِّرُواْ بِهِۦۚ وَلَا تَزَالُ تَطَّلِعُ عَلَىٰ خَآئِنَةٖ مِّنۡهُمۡ إِلَّا قَلِيلٗا مِّنۡهُمۡۖ فَٱعۡفُ عَنۡهُمۡ وَٱصۡفَحۡۚ إِنَّ ٱللَّهَ يُحِبُّ ٱلۡمُحۡسِنِينَ ﴾ [Al-Mā’idah: 13]

(13) So for their breaking of the covenant We cursed them and made their hearts hard. They distort words from their [proper] usages and have forgotten a portion of that of which they were reminded. And you will still observe deceit among them, except a few of them. But pardon them and overlook [their misdeeds]. Indeed, Allah loves the doers of good.

Surah: Al-Mā’idah - Verse: 13 - Juz: 6 - Page: 109

﴿فَلَوۡلَآ إِذۡ جَآءَهُم بَأۡسُنَا تَضَرَّعُواْ وَلَٰكِن قَسَتۡ قُلُوبُهُمۡ وَزَيَّنَ لَهُمُ ٱلشَّيۡطَٰنُ مَا كَانُواْ يَعۡمَلُونَ ﴾ [Al-An‘ām: 43]

(43) Then why, when Our punishment came to them, did they not humble themselves? But their hearts became hardened, and Satan made attractive to them that which they were doing.

Surah: Al-An‘ām - Verse: 43 - Juz: 7 - Page: 132

﴿لِّيَجۡعَلَ مَا يُلۡقِي ٱلشَّيۡطَٰنُ فِتۡنَةٗ لِّلَّذِينَ فِي قُلُوبِهِم مَّرَضٞ وَٱلۡقَاسِيَةِ قُلُوبُهُمۡۗ وَإِنَّ ٱلظَّٰلِمِينَ لَفِي شِقَاقِۭ بَعِيدٖ ﴾ [Al-Ḥajj: 53]

(53) [That is] so He may make what Satan throws in a trial for those within whose hearts is disease and those hard of heart. And indeed, the wrongdoers are in extreme dissension.

Surah: Al-Ḥajj - Verse: 53 - Juz: 17 - Page: 338

﴿أَفَمَن شَرَحَ ٱللَّهُ صَدۡرَهُۥ لِلۡإِسۡلَٰمِ فَهُوَ عَلَىٰ نُورٖ مِّن رَّبِّهِۦۚ فَوَيۡلٞ لِّلۡقَٰسِيَةِ قُلُوبُهُم مِّن ذِكۡرِ ٱللَّهِۚ أُوْلَٰٓئِكَ فِي ضَلَٰلٖ مُّبِينٍ ﴾ [Az-Zumar: 22]

(22) So is one whose breast Allah has expanded to [accept] Islam and he is upon a light from his Lord [like one whose heart rejects it]? Then woe to those whose hearts are hardened against the remembrance of Allah. Those are in manifest error.

Surah: Az-Zumar - Verse: 22 - Juz: 23 - Page: 461

﴿۞ أَلَمۡ يَأۡنِ لِلَّذِينَ ءَامَنُوٓاْ أَن تَخۡشَعَ قُلُوبُهُمۡ لِذِكۡرِ ٱللَّهِ وَمَا نَزَلَ مِنَ ٱلۡحَقِّ وَلَا يَكُونُواْ كَٱلَّذِينَ أُوتُواْ ٱلۡكِتَٰبَ مِن قَبۡلُ فَطَالَ عَلَيۡهِمُ ٱلۡأَمَدُ فَقَسَتۡ قُلُوبُهُمۡۖ وَكَثِيرٞ مِّنۡهُمۡ فَٰسِقُونَ ﴾ [Al-Ḥadīd: 16]

(16) Has the time not come for those who have believed that their hearts should become humbly submissive at the remembrance of Allah and what has come down of the truth? And let them not be like those who were given the Scripture before, and a long period passed over them, so their hearts hardened; and many of them are defiantly disobedient.

Surah: Al-Ḥadīd - Verse: 16 - Juz: 27 - Page: 539