Deuteronomy 4:41-45

Then Moses severed three cities on this side Jordan toward the sunrising;

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:

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.

And this is the law which Moses set before the children of Israel:

These are the testimonies, and the statutes, and the judgments, which Moses spake unto the children of Israel, after they came forth out of Egypt,