Numbers 32
20 Then Moses said to them, "If you will do this—if you will arm yourselves before the Lord for battle, 21 and if all of you will go armed over 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 from your obligation to the Lord and to Israel. And this land will be your possession before the Lord.
23 "But if you fail to do this, you will be sinning against the Lord; and you may be sure that your sin will find you out.
