They were [left], to prove Israel by them, to know whether they would listen to the commandments of Yahweh, which he commanded their fathers by Moses.
      I. How wisely God permitted them to remain. It is mentioned in the close of the foregoing chapter as an act of God's justice, that he let them remain for Israel's correction. But here another construction is put upon it, and it appears to have been an act of God's wisdom, that he let them remain for Israel's real advantage, that those who had not known the wars of Canaan might learn war,Judges 3:1; Judges 3:2. It was the will of God that the people of Israel should be inured to war, 1. Because their country was exceedingly rich and fruitful, and abounded with dainties of all sorts, which, if they were not sometimes made to know hardship, would be in danger of sinking them into the utmost degree of luxury and effeminacy. They must sometimes wade in blood, and not always in milk and honey, lest even their men of war, by the long disuse of arms, should become as soft and as nice as the tender and delicate woman, that would not set so much as the sole of her foot to the ground for tenderness and delicacy, a temper as destructive to every thing that is good as it is to every thing that is great, and therefore to be carefully watched against by all God's Israel. 2. Because their country lay very much in the midst of enemies, by whom they must expect to be insulted; for God's heritage was a speckled bird; the birds round about were against her,Jeremiah 12:9. It was therefore necessary they should be well disciplined, that they might defend their coasts when invaded, and might hereafter enlarge their coast as God had promised them. The art of war is best learnt by experience, which not only acquaints men with martial discipline, but (which is no less necessary) inspires them with a martial disposition. It was for the interest of Israel to breed soldiers, as it is the interest of an island to breed sea-men, and therefore God left Canaanites among them, that, by the less difficulties and hardships they met with in encountering them, they might be prepared for greater, and, by running with the footmen, might learn to contend with horses,Jeremiah 12:5. Israel was a figure of the church militant, that must fight its way to a triumphant state. The soldiers of Christ must endure hardness, 2 Timothy 2:3. Corruption is therefore left remaining in the hearts even of good Christians, that they may learn war, may keep on the whole armour of God, and stand continually upon their guard. The learned bishop Patrick offers another sense of Judges 3:2; Judges 3:2: That they might know to teach them war, that is, they shall know what it is to be left to themselves. Their fathers fought by a divine power. God taught their hands to war and their fingers to fight; but now that they have forfeited his favour let them learn what it is to fight like other men.