Numbers 32:20-27

20And Moses said unto them, If ye will do this thing, if ye will arm yourselves to go before Jehovah to the war, 21and every armed man of you will pass over the Jordan before Jehovah, until he hath driven out his enemies from before him, 22and the land is subdued before Jehovah; then afterward ye shall return, and be guiltless towards Jehovah, and towards Israel; and this land shall be unto you for a possession before Jehovah. 23But if ye will not do so, behold, ye have sinned against Jehovah; and be sure your sin will find you out. 24Build you cities for your little ones, and folds for your sheep; and do that which hath proceeded out of your mouth. 25And the children of Gad and the children of Reuben spake unto Moses, saying, Thy servants will do as my lord commandeth. 26Our little ones, our wives, our flocks, and all our cattle, shall be there in the cities of Gilead; 27but thy servants will pass over, every man that is armed for war, before Jehovah to battle, as my lord saith.