Numbers 31:21
And Eleazar the priest said unto the men of war which went to the battle, This is the ordinance of the law which the LORD commanded Moses; And Eleazar the priest said unto the men of war which went to the battle, This is the ordinance of the law which the LORD commanded Moses;
The ordinance announced by the priest belonged to the history of Israel's war against the Midianites, which was ordered as divine judgment upon them for seducing Israel into sin. The command was carried out without delay, with a thousand fighting men taken from each tribe for the expedition. The force went forth under the leadership of Phinehas, and in the ensuing conflict the kings of Midian and their allies were slain.