Avenge the Lord of Midian - The war against the Midianites was no ordinary war. It was indeed less a war than the execution of a divine sentence against a most guilty people.
Doubtless there were many among the Midianites who were personally guiltless as regards Israel. But the rulers deliberately adopted the counsel of Balaam against Israel, and their behests had been but too readily obeyed by their subjects. The sin therefore was national, and the retribution could be no less so.
But the commission of the Israelites in the text must not be conceived as a general license to slay. They had no discretion to kill or to spare. They were bidden to exterminate without mercy, and brought back to their task Numbers 31:14 when they showed signs of flinching from it. They had no alternarive in this and similar matters except to fulfill the commands of God; an awful but doubtless salutary manifestation, as was afterward the slaughter of the Canaanites, of God’s wrath against sin; and a type of the future extermination of sin and sinners from His kingdom.