Numbers 35:12-15

12And ye shall have these cities for refuge from the avenger; that the manslayer die not, until he have stood before the assembly in judgment.

13And the cities that ye shall give shall be six cities of refuge for you.

14Three cities shall ye give on this side of the Jordan, and three cities shall ye give in the land of Canaan; they shall be cities of refuge.

15For the children of Israel, and for the stranger, and for the sojourner among them shall these six cities be a refuge, that one who smiteth a person mortally without intent may flee thither.