Deuteronomy 19:11-13

11But if someone hates his neighbor, lies in ambush for him, attacks him, and strikes him fatally, and flees to one of these cities,

12the elders of his city are to send for him, take him from there, and hand him over to the avenger of blood and he will die.

13Do not look on him with pity but purge from Israel the guilt of shedding innocent blood, and you will prosper.