It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that a questioner asked him: O Abu al-Abbas, is there any repentance for a killer? Ibn Abbas (may Allah be pleased with them both) said in astonishment: What are you saying? He repeated the question, and he said to him two or three times: What are you saying? Then Ibn Abbas (may Allah be pleased with them both) said: How could he be granted repentance? I heard your Prophet ((peace and blessings be upon him)) say: "The slain person will come (on the Day of Resurrection) holding his head in one hand and gripping his killer by the collar with the other hand, his veins gushing blood, until he brings him to the Throne. The slain person will say to Allah: My Lord, this man killed me. Allah, the Mighty and Majestic, will say to the killer: May you be ruined! And he will be taken to Hellfire."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10696