Deuteronomy 19:1-3

“When the LORD your God destroys the nations whose land he is giving you, you will take over their land and settle in their towns and homes. Then you must set apart three cities of refuge in the land the LORD your God is giving you. Survey the territory, and divide the land the LORD your God is giving you into three districts, with one of these cities in each district. Then anyone who has killed someone can flee to one of the cities of refuge for safety.