﴿ وَلَيْسَتِ ٱلتَّوْبَةُ لِلَّذِينَ يَعْمَلُونَ ٱلسَّيِّـَٔاتِ حَتَّىٰٓ إِذَا حَضَرَ أَحَدَهُمُ ٱلْمَوْتُ قَالَ إِنِّى تُبْتُ ٱلْـَٰٔنَ وَلَا ٱلَّذِينَ يَمُوتُونَ وَهُمْ كُفَّارٌ ۚ أُو۟لَٰٓئِكَ أَعْتَدْنَا لَهُمْ عَذَابًا أَلِيمًۭا ﴾

“whereas repentance shall not be accepted from those who do evil deeds until their dying hour and then say, "Behold, I now repent"; nor from those who die as deniers of the truth: it is these for whom We have readied grievous suffering.”

Repentance is not for those who do evil deeds sins until when death approaches one of them and the pangs of death begin he says upon witnessing his predicament ‘Indeed now I repent’ for this would not avail him and would not be accepted from him; neither for those who die disbelieving if they repent in the Hereafter upon seeing the chastisement it will not be accepted from them. Those — We have prepared for them a painful chastisement.