Numbers 32:18

14 Now behold, you, a brood of sinners, have risen up in place of your fathers to further stoke the burning anger of the LORD against Israel.

15 For if you turn away from following Him, He will once again leave this people in the wilderness, and you will be the cause of their destruction.”

16 Then the Gadites and Reubenites approached Moses and said, “We want to build sheepfolds here for our livestock and cities for our little ones.

17 But we will arm ourselves and be ready to go ahead of the Israelites until we have brought them into their place. Meanwhile, our little ones will remain in the fortified cities for protection from the inhabitants of the land.

18 We will not return to our homes until every Israelite has taken possession of his inheritance.

19 Yet we will not have an inheritance with them across the Jordan and beyond, because our inheritance has come to us on the east side of the Jordan.”

20 Moses replied, “If you will do this—if you will arm yourselves before the LORD for battle,

21 and if every one of your armed men crosses the Jordan before the LORD, until He has driven His enemies out before Him,

22 then when the land is subdued before the LORD, you may return and be free of obligation to the LORD and to Israel. And this land will belong to you as a possession before the LORD.

Read all of Numbers 32