Sunan An Nasai 4870

أَخْبَرَنَا قُتَيْبَةُ، ‏‏‏‏‏‏قَالَ:‏‏‏‏ حَدَّثَنَا سُفْيَانُ، ‏‏‏‏‏‏عَنْ عَمَّارٍ الدُّهْنِيِّ، ‏‏‏‏‏‏عَنْ سَالِمِ بْنِ أَبِي الْجَعْدِ، ‏‏‏‏‏‏أَنَّ ابْنَ عَبَّاسٍ سُئِلَ عَمَّنْ قَتَلَ مُؤْمِنًا مُتَعَمِّدًا، ‏‏‏‏‏‏ثُمَّ تَابَ، ‏‏‏‏‏‏وَآمَنَ وَعَمِلَ صَالِحًا، ‏‏‏‏‏‏ثُمَّ اهْتَدَى ؟ فَقَالَ ابْنُ عَبَّاسٍ:‏‏‏‏ وَأَنَّى لَهُ التَّوْبَةُ، ‏‏‏‏‏‏سَمِعْتُ نَبِيَّكُمْ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ، ‏‏‏‏‏‏يَقُولُ:‏‏‏‏ يَجِيءُ مُتَعَلِّقًا بِالْقَاتِلِ تَشْخَبُ أَوْدَاجُهُ دَمًا يَقُولُ:‏‏‏‏ سَلْ هَذَا فِيمَ قَتَلَنِي ؟ ،‏‏‏‏ ثُمَّ قَالَ:‏‏‏‏ وَاللَّهِ لَقَدْ أَنْزَلَهَا وَمَا نَسَخَهَا.

It was narrated from Salim bin abi Ja'd that: Ibn 'Abbas was asked about someone who killed a believer deliberately then he repented, believed and did righteous deeds, and followed true guidance. Ibn 'Abbas said: There is no way he could repent! I heard your Prophet say; He (the victim) will come hanging onto his killer with his jugular veins flowing with blood and saying: Ask him why he killed me. Then he said: by Allah, Allah revealed it and never abrogated anything of it.