Deuteronomy 19:11-13

11“But 1if there is a man who hates his neighbor and lies in wait for him and rises up against him and strikes 2him so that he dies, and he flees to one of these cities, 12then the elders of his city shall send and take him from there and deliver him into the hand of the avenger of blood, that he may die. 1334You shall not pity him, but 5you shall purge the blood of the innocent from Israel, that it may go well with you.