Concerning the verse, "And whoever kills a believer intentionally" [Surah al-Nisa: 93], Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "There is no repentance for the killer of a believer; no verse has abrogated it since it was revealed."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12262