Keil & Delitzsch, on Judg 8:24

Gideon resisted the temptation to put an earthly crown upon his head, from true fidelity to Jehovah; but he yielded to another temptation, which this appeal on the part of the people really involved, namely, the temptation to secure to himself for the future the position to which the Lord had called and exalted him. The Lord had called him to be the deliverer of Israel by visibly appearing in His angel, and had not only accepted the gift which he offered Him, as a well-pleasing sacrifice, but had also commanded him to build an altar, and by offering an atoning burnt-sacrifice to re-establish the worship of Jehovah in his family and tribe, and to restore the favour of God to His people once more. Lastly, the Lord had made His will known to him again and again; whilst by the glorious victory which He had given to him and to his small band over the powerful army of the foe, He had confirmed him as His chosen servant to be the deliverer and judge of Israel. The relation which Gideon thus sustained to the Lord he imagined that he ought to preserve; and therefore, after declining the royal dignity, he said to the people, "I will request of you one request, that ye give me every one the ring that he has received as booty." This request the historian explains by adding the remark: "for they (the enemy) had golden rings, for they were Ishmaelites," from whom therefore the Israelites were able to get an abundance of rings as booty. Ishmaelites is the general name for the nomad tribes of Arabia, to whom the Midianites also belonged (as in Gen 37:25).