Deuteronomy 19:2

1 When the Yahuah your Elohim has cut off the nations, whose land the Yahuah your Elohim giveth you, and you succeedest them, and dwellest in their cities, and in their houses;

2 you shall separate three cities for you in the midst of your land, which the Yahuah your Elohim giveth you to possess it.

3 you shall prepare you a way, and divide the coasts of your land, which the Yahuah your Elohim giveth you to inherit, into three parts, that every slayer may flee thither.

4 And this 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;