Numbers 32:30

27 But thy servants will pass over, every man armed for war, before the LORD to battle, as my lord saith.

28 So concerning them Moses commanded Eleazar the priest, and Joshua the son of Nun, and the chief fathers of the tribes of the children of Israel:

29 And Moses said to them, If the children of Gad and the children of Reuben will pass with you over Jordan, every man armed for battle, before the LORD, and the land shall be subdued before you; then ye shall give them the land of Gilead for a possession:

30 But if they will not pass over with you armed, they shall have possessions among you in the land of Canaan.

31 And the children of Gad and the children of Reuben answered, saying, As the LORD hath said to thy servants, so will we do.

32 We will pass over armed before the LORD into the land of Canaan, that the possession of our inheritance on this side Jordan [may be] ours.

33 And Moses gave to them, [even] to the children of Gad, and to the children of Reuben, and to half the tribe of Manasseh the son of Joseph, the kingdom of Sihon king of the Amorites, and the kingdom of Og king of Bashan, the land, with its cities in the borders, [even] the cities of the country around.