Avenge ye the Lord — For the affront which they offered to God, by their own idolatry and lewdness, and by seducing God's people into rebellion against him. God's great care was to avenge the Israelites, Numbers 31:2, and Moses's chief desire was to avenge God rather than himself or the people.
Related Commentaries of Numbers 31:3
Numbers 31:3
3 And Moses spake unto the people, saying, Arm some of yourselves unto the war, and let them go against the Midianites, and avenge the LORD of Midian.