Num 35.15These six cities shall be a refuge, both for the children of Israel, and for the stranger, and for the sojourner among them: that every one that killeth any person unawares may flee thither.
Deut 4.42That the slayer might flee thither, which should kill his neighbor unawares, and hated him not in times past; and that fleeing unto one of these cities he might live: