“When the LORD your God cuts off the nations whose land the LORD your God is giving you, and you dispossess them and dwell in their cities and in their houses, you shall set apart three cities for yourselves in the land that the LORD your God is giving you to possess. You shall measure the distances 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. “This is the provision for the manslayer, who by fleeing there may save his life. If anyone kills his neighbor unintentionally without having hated him in the past— as when someone goes into the forest with his neighbor to cut wood, and his hand swings the axe to cut down a tree, and the head slips from the handle and strikes his neighbor so that he dies—he may flee to one of these cities and live, lest the avenger of blood in hot anger pursue the manslayer and overtake him, because the way is long, and strike him fatally, though the man did not deserve to die, since he had not hated his neighbor in the past. Therefore I command you, You shall set apart three cities.
English Standard Version (ESV)