Ibn Abbas was asked about a man who killed a believer, then repented, believed, did righteous deeds, and was guided.He replied, "Woe to you, how can he be guided? I heard your Prophet ﷺ say, 'The murdered man will come clinging to his killer, saying, My Lord, ask this man why he killed me.' By Allah, Allah revealed this verse to your Prophet ﷺ and did not abrogate it after revealing it."He then said, "Woe to you, how can he be guided?"
حدثنا سفيان عن عمار
سئل ابن عباس عن رجل قتل مؤمنا ثم تاب وآمن وعمل صالحا ثم اهتدى قال ويحك وأنى له الهدى سمعت نبيكم ﷺ يقول يجيء المقتول متعلقا بالقاتل يقول يا رب سل هذا فيم قتلني والله لقد أنزلها الله عز وجل على نبيكم ﷺ وما نسخها بعد إذ أنزلها قال ويحك وأنى له الهدى
Its isnad is sahih. Ammar is Ibn Muawiya Duhni, with the dal pronounced with damma and the ha with sukun, and he is trustworthy. Salim is Ibn Abu Jaad. The hadith is an abridged version of 2142, 2683. It was also narrated with a similar meaning by Bukhari, Muslim, Nasai, and Abu Dawud, and it was narrated through this route by Nasai and Ibn Majah. See tafsir Ibn Kathir 2:537-539. It will come again at 2142, 2683.