Numbers 32:9

Numbers 32 records how the tribes of Reuben and Gad, who had great flocks, asked to settle in the lands of Jazer and Gilead east of the Jordan rather than cross into Canaan. Moses rebuked them for discouraging the rest of Israel as the spies had done, but they pledged to arm themselves and lead the vanguard in the conquest until every tribe had its inheritance. Moses agreed, granting them the land on that condition, and they built folds for their sheep while their fighting men prepared to cross over.