Numbers 32:18-33
We will not return to our homes until each of the people of Israel has gained his inheritance.For we will not inherit with them on the other side of the Jordan and beyond, because our inheritance has come to us on this side of the Jordan to the east.”So Moses said to them,“ If you will do this, if you will take up arms to go before the Lord for the war,and every armed man of you will pass over the Jordan before the Lord, until he has driven out his enemies from before himand the land is subdued before the Lord; then after that you shall return and be free of obligation to the Lord and to Israel, and this land shall be your possession before the Lord.But if you will not do so, behold, you have sinned against the Lord, and be sure your sin will find you out.Build cities for your little ones and folds for your sheep, and do what you have promised.”And the people of Gad and the people of Reuben said to Moses,“ Your servants will do as my lord commands.Our little ones, our wives, our livestock, and all our cattle shall remain there in the cities of Gilead,but your servants will pass over, every man who is armed for war, before the Lord to battle, as my lord orders.”So Moses gave command concerning them to Eleazar the priest and to Joshua the son of Nun and to the heads of the fathers’ houses of the tribes of the people of Israel.And Moses said to them,“ If the people of Gad and the people of Reuben, every man who is armed to battle before the Lord, will pass with you over the Jordan and the land shall be subdued before you, then you shall give them the land of Gilead for a possession.However, if they will not pass over with you armed, they shall have possessions among you in the land of Canaan.”And the people of Gad and the people of Reuben answered,“ What the Lord has said to your servants, we will do.We will pass over armed before the Lord into the land of Canaan, and the possession of our inheritance shall remain with us beyond the Jordan.”And Moses gave to them, to the people of Gad and to the people of Reuben and to the half-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 and its cities with their territories, the cities of the land throughout the country.