Numbers 32:29

32:29 Moses said to them: “If the Gadites and the Reubenites cross the Jordan with you, each one equipped for battle in the Lord’s presence, and you conquer the land, then you must allot them the territory of Gilead as their possession.

Numbers 35:8

35:8 The towns you will give must be from the possession of the Israelites. From the larger tribes you must give more; and from the smaller tribes fewer. Each must contribute some of its own towns to the Levites in proportion to the inheritance allocated to each.