It was narrated that Salim bin Abu Jad said:
"Ibn Abbas was asked about one who kills a believer deliberately, then repents, believes, does righteous deeds and follows true guidance. He said: 'Woe to him can there be any guidance for him? I heard your Prophet (ﷺ) say: "The killer and his victim will be brought on the day of Resurrection, with slain holding onto the head of his killer, saying: 'O Lord, ask this one, why did he kill me?" By Allah (SWT), Allah (SWT) the Mighty and Sublime revealed it to your Prophet (ﷺ) then He did not abrogate it after He revealed it."
English reference: Vol. 3, Book 21, Hadith 2621
Arabic reference: Book 21, Hadith 2719