Deuteronomy 19:1-6
Laws Concerning Manslaughter
19:1 When the Lord your God destroys the nations whose land he is about to give you and you dispossess them and settle in their cities and houses,
19:2 you must set apart for yourselves three cities in the middle of your land that the Lord your God is giving you as a possession.
19:3 You shall build a roadway and divide into thirds the whole extent of your land that the Lord your God is providing as your inheritance; anyone who kills another person should flee to the closest of these cities.
19:4 Now this is the law pertaining to one who flees there in order to live, if he has accidentally killed another without hating him at the time of the accident.
19:5 Suppose he goes with someone else to the forest to cut wood and when he raises the ax to cut the tree, the ax head flies loose from the handle and strikes his fellow worker so hard that he dies. The person responsible may then flee to one of these cities to save himself.
19:6 Otherwise the blood avenger will chase after the killer in the heat of his anger, eventually overtake him, and kill him, though this is not a capital case since he did not hate him at the time of the accident.