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 32:33

Land Assignment

32:33 So Moses gave to the Gadites, the Reubenites, and to half the tribe of Manasseh son of Joseph the realm of King Sihon of the Amorites, and the realm of King Og of Bashan, the entire land with its cities and the territory surrounding them.

Numbers 35:5

35:5 “You must measure from outside the wall of the town on the east 1,000 yards, and on the south side 1,000 yards, and on the west side 1,000 yards, and on the north side 1,000 yards, with the town in the middle. This territory must belong to them as grazing land for the towns.