وَلَيْسَتِ ٱلتَّوْبَةُ لِلَّذِينَ يَعْمَلُونَ ٱلسَّيِّئَاتِ حَتَّىٰ إِذَا حَضَرَ أَحَدَهُمُ ٱلْمَوْتُ قَالَ إِنِّى تُبْتُ ٱلآنَ وَلاَ ٱلَّذِينَ يَمُوتُونَ وَهُمْ كُفَّارٌ أُوْلَـٰئِكَ أَعْتَدْنَا لَهُمْ عَذَاباً أَلِيما

Qur’an says:

There is no repentance for those who persist in their evil deeds until death approaches anyone of them and he says: “surely now I repent.” Similarly, there is no repentance for those who die while they were still unbelievers; for them. We have prepared a painful punishment (Qur’an, 4: 18)