Numbers 35:11-15

11then ye shall appoint you cities to be cities of refuge for you, that the manslayer that killeth any person unwittingly may flee thither. 12And the cities shall be unto you for refuge from the avenger, that the manslayer die not, until he stand before the congregation for judgment. 13And the cities which ye shall give shall be for you six cities of refuge. 14Ye shall give three cities beyond 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 for refuge; that every one that killeth any person unwittingly may flee thither.