Deuteronomy 4:41-43

41 ¶ Then Moses severed three cities on this side Jordan toward the sunrising; 42 That the slayer might flee thither, which should kill his neighbour unawares, and hated him not in times past; and that fleeing unto one of these cities he might live: 43 Namely, Bezer in the wilderness, in the plain country, of the Reubenites; and Ramoth in Gilead, of the Gadites; and Golan in Bashan, of the Manassites.