Numbers 32:23-27

But if you do not do this, behold, you will have sinned against the LORD; and be sure that your sin will find you out. Build yourselves cities for your children, and folds for your sheep, and do that of which you have spoken.” Then the descendants of Gad and of Reuben said to Moses, “Your servants will do just as my lord commands. Our children, our wives, our livestock, and all our cattle shall be there in the cities of Gilead. But your servants will cross over, every man armed for war, before the LORD to the battle, just as my lord says.”