Deuteronomy 19:3
You are to build roads for yourselves and divide into three regions the land that the LORD your God is giving you as an inheritance, so that any manslayer can flee to these cities.
Berean Standard Bible
Thou shalt prepare thee a way, and divide the coasts of thy land, which the LORD thy God giveth thee to inherit, into three parts, that every slayer may flee thither.
You shall prepare the way, and divide the borders of your land which the LORD your God causes you to inherit into three parts, that every man slayer may flee there.