Numbers 32:20-27

20Moses said to them, “If you will do this—if you will arm yourselves for battle for Adonai,

21and if all of you cross the Jordan until Adonai has driven His enemies from before Him

22and the land is subdued before Adonai—then afterward you may return and be free before Adonai and Israel. Then this territory will be your possession before Adonai.

23“But if you don’t do this, behold, you sin against Adonai! Be assured! Your sin will find you out!

24Build for yourselves cities for your children and pens for your flocks. Then do what has come out of your mouth.”

25The sons of Gad and Reuben said to Moses saying, “Your servants will do just as my lord is commanding.

26Our children, our wives, our flocks, and all of our herds will remain here in the cities of Gilead.

27But your servants, every one armed for battle, will cross over for the war before Adonai, just as my lord says.”