Deuteronomy 19:3

Thou shalt prepare thee a way, keep the roads to these cities in good condition, the passage of the rivers and creeks being an item of great importance, and divide the coasts of thy land, which the Lord, thy God, giveth thee to inherit, into three parts, namely, with reference to the eventual central location of the cities of refuge, that every slayer may flee thither, no distinction being made here between one whose life would be preserved and one who would eventually be condemned as a murderer.