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 ourselves will be armed, ready to go before the children of Israel until we have brought them to their place; and our little ones will dwell in the fortified cities because of the inhabitants of the land. We will not return to our homes until every one of the children of Israel has received his inheritance. For we will not inherit with them on the other side of the Jordan and beyond, because our inheritance has fallen to us on this eastern side of the Jordan.” Then Moses said to them: “If you do this thing, if you arm yourselves before the LORD for the war, and all your armed men cross 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 may return and be blameless before the LORD and before Israel; and this land shall be your possession before the LORD. But if you do not do so, then take note, you have sinned against the LORD; and be sure your sin will find you out.