Numbers 32:20-28

20So Moses said to them, “If you will do this, if you will take up arms to go before the LORD for the war, 21and every armed man of you will pass over the Jordan before the LORD, until he has driven out his enemies from before him 22and 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. 23But if you will not do so, behold, you have sinned against the LORD, and be sure your sin will find you out. 24Build cities for your little ones and folds for your sheep, and do what you have promised.” 25And the people of Gad and the people of Reuben said to Moses, “Your servants will do as my lord commands. 26Our little ones, our wives, our livestock, and all our cattle shall remain there in the cities of Gilead, 27but your servants will pass over, every man who is armed for war, before the LORD to battle, as my lord orders.” 28So Moses gave command concerning them to Eleazar the priest and to Joshua the son of Nun and to the heads of the fathers’ houses of the tribes of the people of Israel.