Numbers 32:16-23

Then they came near to him and said, “We will build sheepfolds here for our livestock, and cities for our little ones, but we will take up arms, ready to go before the people of Israel, until we have brought them to their place. And our little ones shall live in the fortified cities because of the inhabitants of the land. 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 him and 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.