Numbers 32:16-27

16And they came near unto him, and said, We will build sheepfolds here for our cattle, and cities for our little ones: 17But we ourselves will go ready armed before the children of Israel, until we have brought them unto their place: and our little ones shall dwell in the fenced cities because of the inhabitants of the land. 18We will not return unto our houses, until the children of Israel have inherited every man his inheritance. 19For we will not inherit with them on yonder side Jordan, or forward; because our inheritance is fallen to us on this side Jordan eastward.

20And Moses said unto them, If ye will do this thing, if ye will go armed before Yhwh to war, 21And will go all of you armed over Jordan before Yhwh, until he hath driven out his enemies from before him, 22And the land be subdued before Yhwh: then afterward ye shall return, and be guiltless before Yhwh, and before Israel; and this land shall be your possession before Yhwh. 23But if ye will not do so, behold, ye have sinned against Yhwh: and be sure your sin will find you out. 24Build you cities for your little ones, and folds for your sheep; and do that which hath proceeded out of your mouth. 25And the children of Gad and the children of Reuben spake unto Moses, saying, Thy servants will do as my lord commandeth. 26Our little ones, our wives, our flocks, and all our cattle, shall be there in the cities of Gilead: 27But thy servants will pass over, every man armed for war, before Yhwh to battle, as my lord saith.