Deuteronomy 19:2-4

King James Version

² Thou shalt separate three cities for thee in the midst of thy land, which the Lord thy God giveth thee to possess it.

³ 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.

⁴ And this is the case of the slayer, which shall flee thither, that he may live: Whoso killeth his neighbour ignorantly, whom he hated not in time past;