Deuteronomy 4:41-43

Thomson(i) 41 Then Moses set apart three cities on the side of Jordan, towards the rising of the sun, 42 for the slayer to flee to. Whoever should kill his neighbour unawares, and hated him not in times past, might flee to one of these cities, and live, 43 namely, Bosor, in the wilderness, in the plain, for the Reubenites; and Bamoth, in Galaaditis, for the Gadites; and Gaulon, in Basan, for the Manassites.