A mass murderer can be forgiven on repenting before death

The Prophet of Allah ﷺ said: “Among those who came before you there was a man who killed ninety-nine people. He asked about the most knowledgeable person on earth, and he was directed to a monk. He went to him and said that he had killed ninety-nine people—was there any repentance for him? He said, ‘No,’ so he killed him, thereby completing one hundred. Then he asked about the most knowledgeable person on earth, and he was directed to a learned man. He said that he had killed one hundred people—was there any repentance for him? He said, ‘Yes—and who could stand between him and repentance? Go to such-and-such a land, for there are people there who worship Allah; worship Allah with them, and do not return to your land, for it is an evil land.’"

“So he set out, and when he had reached halfway along the road, death came to him. The angels of mercy and the angels of punishment disputed concerning him. The angels of mercy said, ‘He came repentant, turning with his heart toward Allah.’ The angels of punishment said, ‘He has never done any good at all.’ Then an angel came to them in the form of a human being, and they made him judge between them. He said, ‘Measure the distance between the two lands; whichever of them he is closer to, he belongs to it.’ So they measured, and found him closer to the land he had intended, and the angels of mercy took him.”

أَنَّ نَبِيَّ اللَّهِ ﷺ قَالَ: «كَانَ فِيمَنْ كَانَ قَبْلَكُمْ رَجُلٌ قَتَلَ تِسْعَةً وَتِسْعِينَ نَفْسًا۔ فَسَأَلَ عَنْ أَعْلَمِ أَهْلِ الأَرْضِ، فَدُلَّ عَلَى رَاهِبٍ۔ فَأَتَاهُ فَقَالَ إِنَّهُ قَتَلَ تِسْعَةً وَتِسْعِينَ نَفْسًا فَهَلْ لَهُ مِنَ تَوْبَةٍ۔ فَقَالَ لاَ، فَقَتَلَهُ فَكَمَّلَ بِهِ مِائَةً۔ ثُمَّ سَأَلَ عَنْ أَعْلَمِ أَهْلِ الأَرْضِ، فَدُلَّ عَلَى رَجُلٍ عَالِمٍ۔ فَقَالَ إِنَّهُ قَتَلَ مِائَةَ نَفْسٍ فَهَلْ لَهُ مِنْ تَوْبَةٍ۔ فَقَالَ نَعَمْ وَمَنْ يَحُولُ بَيْنَهُ وَبَيْنَ التَّوْبَةِ؟ انْطَلِقْ إِلَى أَرْضِ كَذَا وَكَذَا فَإِنَّ بِهَا أُنَاسًا يَعْبُدُونَ اللَّهَ، فَاعْبُدِ اللَّهَ مَعَهُمْ وَلاَ تَرْجِعْ إِلَى أَرْضِكَ فَإِنَّهَا أَرْضُ سَوْءٍ»،

«فَانْطَلَقَ حَتَّى إِذَا نَصَفَ الطَّرِيقَ أَتَاهُ الْمَوْتُ، فَاخْتَصَمَتْ فِيهِ مَلاَئِكَةُ الرَّحْمَةِ وَمَلاَئِكَةُ الْعَذَابِ۔ فَقَالَتْ مَلاَئِكَةُ الرَّحْمَةِ: جَاءَ تَائِبًا مُقْبِلاً بِقَلْبِهِ إِلَى اللَّهِ۔ وَقَالَتْ مَلاَئِكَةُ الْعَذَابِ: إِنَّهُ لَمْ يَعْمَلْ خَيْرًا قَطُّ۔ فَأَتَاهُمْ مَلَكٌ فِي صُورَةِ آدَمِيٍّ فَجَعَلُوهُ بَيْنَهُمْ۔ فَقَالَ: قِيسُوا مَا بَيْنَ الأَرْضَيْنِ فَإِلَى أَيَّتِهِمَا كَانَ أَدْنَى فَهُوَ لَهُ۔ فَقَاسُوهُ فَوَجَدُوهُ أَدْنَى إِلَى الأَرْضِ الَّتِي أَرَادَ، فَقَبَضَتْهُ مَلاَئِكَةُ الرَّحْمَةِ».

There is no chance for repentance for you. He killed the monk also and then began to make an inquiry and moved from one village to another village where there lived pious persons, and as he had covered some distance, he was overtaken by death, but he managed to crawl upon his chest (to the side nearer to the place where the pious men lived). He died and then there was a dispute between the angels of mercy and the angels of punishment and (when it was measured) he was found to be nearer to the village where pious persons were living equal to the Space of a span and he was thus included among them.

عَنِ النَّبِيِّ ﷺ أَنَّ رَجُلاً قَتَلَ تِسْعَةً وَتِسْعِينَ نَفْسًا فَجَعَلَ يَسْأَلُ هَلْ لَهُ مِنْ تَوْبَةٍ فَأَتَى رَاهِبًا فَسَأَلَهُ فَقَالَ لَيْسَتْ لَكَ تَوْبَةٌ فَقَتَلَ الرَّاهِبَ ثُمَّ جَعَلَ يَسْأَلُ ثُمَّ خَرَجَ مِنْ قَرْيَةٍ إِلَى قَرْيَةٍ فِيهَا قَوْمٌ صَالِحُونَ فَلَمَّا كَانَ فِي بَعْضِ الطَّرِيقِ أَدْرَكَهُ الْمَوْتُ فَنَأَى بِصَدْرِهِ ثُمَّ مَاتَ فَاخْتَصَمَتْ فِيهِ مَلاَئِكَةُ الرَّحْمَةِ وَمَلاَئِكَةُ الْعَذَابِ فَكَانَ إِلَى الْقَرْيَةِ الصَّالِحَةِ أَقْرَبَ مِنْهَا بِشِبْرٍ فَجُعِلَ مِنْ أَهْلِهَا

" Allah commanded the earth (from where) he wanted to come out to move itself away and to the other earth (where he wanted to go) to draw nearer."

أَنْ تَقَرَّبِي

When it will be the Day of Resurrection Allah would deliver to every Muslim a Jew or a Christian and say: That is your rescue from Hell-Fire.

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا كَانَ يَوْمُ الْقِيَامَةِ دَفَعَ اللَّهُ ﷻ إِلَى كُلِّ مُسْلِمٍ يَهُودِيًّا أَوْ نَصْرَانِيًّا فَيَقُولُ هَذَا فَكَاكُكَ مِنَ النَّارِ

No Muslim would die but Allah would admit in his stead a Jew or a Christian in Hell-Fire. 'Umar b. Abd al-'Aziz took an oath: By One besides Whom there is no god but He, thrice that his father had narrated that to him from Messenger of Allah ﷺ.

عَنِ النَّبِيِّ ﷺ قَالَ لاَ يَمُوتُ رَجُلٌ مُسْلِمٌ إِلاَّ أَدْخَلَ اللَّهُ مَكَانَهُ النَّارَ يَهُودِيًّا أَوْ نَصْرَانِيًّا قَالَ فَاسْتَحْلَفَهُ عُمَرُ بْنُ عَبْدِ الْعَزِيزِ بِاللَّهِ الَّذِي لاَ إِلَهَ إِلاَّ هُوَ ثَلاَثَ مَرَّاتٍ أَنَّ أَبَاهُ حَدَّثَهُ عَنْ رَسُولِ اللَّهِ ﷺ قَالَ فَحَلَفَ لَهُ قَالَ فَلَمْ يُحَدِّثْنِي سَعِيدٌ أَنَّهُ اسْتَحْلَفَهُ وَلَمْ يُنْكِرْ عَلَى عَوْنٍ قَوْلَهُ

This hadith has been transmitted on the authority of 'Aun b. Utba.

حَدَّثَنَا قَتَادَةُ بِهَذَا الإِسْنَادِ نَحْوَ حَدِيثِ عَفَّانَ وَقَالَ عَوْنُ بْنُ عُتْبَةَ

There would come people amongst the Muslims on the Day of Resurrection with as heavy sins as a mountain, and Allah would forgive them and He would place in their stead the Jews and the Christians. (As far as I think), Abu Raub said: I do not know as to who is in doubt. Abu Burda said: I narrated it to 'Umar b. 'Abd al-'Aziz, whereupon he said: Was it your father who narrated it to you from Allah's Apostle ﷺ? I said: Yes.

عَنِ النَّبِيِّ ﷺ قَالَ يَجِيءُ يَوْمَ الْقِيَامَةِ نَاسٌ مِنَ الْمُسْلِمِينَ بِذُنُوبٍ أَمْثَالِ الْجِبَالِ فَيَغْفِرُهَا اللَّهُ لَهُمْ وَيَضَعُهَا عَلَى الْيَهُودِ وَالنَّصَارَى فِيمَا أَحْسِبُ أَنَا قَالَ أَبُو رَوْحٍ لاَ أَدْرِي مِمَّنِ الشَّكُّ قَالَ أَبُو بُرْدَةَ فَحَدَّثْتُ بِهِ عُمَرَ بْنَ عَبْدِ الْعَزِيزِ فَقَالَ أَبُوكَ حَدَّثَكَ هَذَا عَنِ النَّبِيِّ ﷺ قُلْتُ نَعَمْ

How did you hear Messenger of Allah ﷺ as saying something about intimate conversation? He said: I heard him say: A believer will be brought to his Lord, the Exalted and Glorious, on the Day of Resurrection and He would place upon him His veil (of Light) and make him confess his faults and say: Do you recognise (your faults)? He would say: My Lord, I do recognise (them). He (the Lord) would say: I concealed them for you in the world. And today I forgive them. And he would then be given the Book containing (the account of his) good deeds. And so far as the non-believers and hypocrites are concerned, there would be general announcement about them before all creation telling them that these (people, i. e. non-believers and hypocrites) told a lie about Allah.

سَمِعْتَ رَسُولَ اللَّهِ ﷺ يَقُولُ فِي النَّجْوَى قَالَ سَمِعْتُهُ يَقُولُ يُدْنَى الْمُؤْمِنُ يَوْمَ الْقِيَامَةِ مِنْ رَبِّهِ ﷻ حَتَّى يَضَعَ عَلَيْهِ كَنَفَهُ فَيُقَرِّرُهُ بِذُنُوبِهِ فَيَقُولُ هَلْ تَعْرِفُ فَيَقُولُ أَىْ رَبِّ أَعْرِفُ قَالَ فَإِنِّي قَدْ سَتَرْتُهَا عَلَيْكَ فِي الدُّنْيَا وَإِنِّي أَغْفِرُهَا لَكَ الْيَوْمَ فَيُعْطَى صَحِيفَةَ حَسَنَاتِهِ وَأَمَّا الْكُفَّارُ وَالْمُنَافِقُونَ فَيُنَادَى بِهِمْ عَلَى رُءُوسِ الْخَلاَئِقِ هَؤُلاَءِ الَّذِينَ كَذَبُوا عَلَى اللَّهِ