Moshe teaches the rules and restrictions governing oaths and vows, especially the role of a husband or father in either upholding or annulling a vow.  Bnai Yisrael wage war against Midian.  They kill the five Midianite Kings, all the males and Bilaam.

Moshe is upset that women were taken captive, because they were catalysts for the immoral behavior of the Jewish People.  He rebukes the officers. The spoils of war are counted and apportioned.  The commanding officers report to Moshe that there was not one casualty among Bnai Yisrael.  They bring an offering which is taken by Moshe and Elazar and placed in the Ohel Mo'ed (Tent of Meeting).

 The Tribes of Gad and Reuven, who own large quantities of livestock, petition Moshe to allow them to remain east of the Jordan and not enter the Land of Israel.  They explain that the land east of the Jordan is quite suitable grazing land for their livestock.  Moshe's initial response is that this request will discourage the rest of Bnai Yisrael, and that it is akin to the sin of the spies. They assure Moshe that they will first help conquer Israel, and only then will they go back to their homes on the eastern side of the Jordan River.  Moshe grants their request on condition that they uphold their part of the deal.