Deuteronomy 19:2-4

2 ayou shall set apart three cities for yourselves in the land that the Lord your God is giving you to possess. 3You shall measure the distances
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and divide into three parts the area of the land that the Lord your God gives you as a possession, so that any manslayer can flee to them.

4This is the provision for cthe manslayer, who by fleeing there may save his life. If anyone kills his neighbor unintentionally without having hated him in the past
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