31:1-6 All who, without commission from God, dare to execute private revenge, and who, from ambition, covetousness, or resentment, wage war and desolate kingdoms, must one day answer for it. But if God, instead of sending an earthquake, a pestilence, or a famine, be pleased to authorize and command any people to avenge his cause, such a commission surely is just and right. The Israelites could show such a commission, though no persons now can do so. Their wars were begun and carried on expressly by Divine direction, and they were enabled to conquer by miracles. Unless it can be proved that the wicked Canaanites did not deserve their doom, objectors only prove their dislike to God, and their love to his enemies. Man makes light of the evil of sin, but God abhors it. This explains the terrible executions of the nations which had filled the measure of their sins.Of every tribe a thousand,.... So that the whole number of those that were armed were 12,000 as after given:

throughout all the tribes of Israel; this is observed, as Jarchi thinks, to comprehend the tribe of Levi, which in some cases was left out of the account:

shall ye send to the war; to fight with Midian.