Numbers 32:23

19For 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 eastward.”

20Moses said to them: “If you will do this thing, if you will arm yourselves to go before the LORD to the war,

21and every one of your armed men will pass over the Jordan before the LORD until he has driven out his enemies from before him,

22and the land is subdued before the LORD; then afterward you shall return, and be clear of obligation to the LORD and to Israel. Then this land shall be your possession before the LORD.

23“But if you will not do so, behold, you have sinned against the LORD; and be sure your sin will find you out.

24Build cities for your little ones, and folds for your sheep; and do that which has proceeded out of your mouth.”

25The children of Gad and the children of Reuben spoke to Moses, saying, “Your servants will do as my lord commands.

26Our little ones, our wives, our flocks, and all our livestock shall be there in the cities of Gilead;

27but your servants will pass over, every man who is armed for war, before the LORD to battle, as my lord says.”