Numbers 32:16-24

16But the people of Reuben and Gad approached Moses and said, “We will build sheepfolds here for our flocks and [walled] cities for our children,

17but we will be armed and ready to go to war before the [other tribes of the] Israelites, until we have brought them to their place, while our children live in the fortified cities because of the inhabitants of the land.

18We will not return to our homes until every one of the [other] sons of Israel has taken possession of his inheritance.

19For we will not inherit with them on the west side of the Jordan and beyond, because our inheritance has come to us on this side of the Jordan [River] toward the east.”

20Moses replied, “If you will do as you say, if you will arm yourselves before the Lord for war,

21and every armed man of yours will cross the Jordan before the Lord until He has driven out His enemies before Him,

22and the land [west of the Jordan] is subdued before the Lord, then afterward you shall return and be blameless [in this matter] before the Lord and before Israel, and this land [east of the Jordan] shall be yours as a possession before the Lord.

23But if you do not do this, behold, you will have sinned against the Lord; and be sure that your sin will find you out.

24Build yourselves cities for your children, and folds for your sheep, and do that of which you have spoken.”