Deuteronomy 19
3 Ref 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 Ref And this is the case of the slayer, which shall flee thither, that he may live: Whoso killeth his neighbor ignorantly, whom he hated not in time past;