John Gills Exposition of the Bible Commentary - Numbers 31:5
So they were delivered out of the thousands of Israel ,.... Several thousands very probably offered themselves voluntarily to go to the war, or however were summoned together on this account, and out of them the following number was delivered of picked and chosen men: a thousand of every tribe, twelve thousand armed for war ; which was but a small number to go against so considerable a nation and people; but this was done to show that the war was of the Lord, he would fight the battle,... read more
Matthew Henry's Complete Commentary - Numbers 31:1-6
Here, I. The Lord of hosts gives orders to Moses to make war upon the Midianites, and his commission no doubt justified this war, though it will not serve to justify the like without such commission. The Midianites were the posterity of Abraham by Keturah, Gen. 25:2. Some of them settled south of Canaan, among whom Jethro lived, and they retained the worship of the true God; but these were settled east of Canaan, and had fallen into idolatry, neighbours to, and in confederacy with, the... read more