Deuteronomy 4:42-46

for one to flee there who unintentionally killed his neighbor, without having hatred for him in time past; and by fleeing to one of these cities he might live:

Bezer in the wilderness on the plateau for the Reubenites, Ramoth in Gilead for the Gadites, and Golan in Bashan for the Manassites.

Now this is the Law which Moses set before the sons of Israel;

these are the testimonies and the statutes, and the ordinances which Moses spoke to the sons of Israel, when they came out of Egypt,

across the Jordan, in the valley opposite Beth-peor, in the land of Sihon king of the Amorites who lived in Heshbon, whom Moses and the sons of Israel defeated when they came out of Egypt.