Numbers 32:24

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

and 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.

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

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

Our little ones, our wives, our flocks, and all our livestock shall be 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 says.”