Let the redeemed of the Lord say so - They are especially qualified to say so; they have special occasion to say so; they can and will appreciate this trait in his character. The word rendered "redeemed" here - from גאל gā'al - means "delivered, rescued," without reference to any price paid for the deliverance. It refers here not to a ransom from "sin," but to deliverance from "danger." The probable allusion is to the deliverance from the captivity in Babylon. Compare the notes at Isaiah 43:3.
Whom he hath redeemed from the hand of the enemy - the power of the enemy. That is, He has saved them from their enemies, and has not suffered them to be destroyed by them. What is here said is true in the most eminent sense of those who are redeemed by the blood of the Son of God, and who are made heirs of salvation. Every consideration makes it proper that they should praise the Lord. Of all on earth, they have most occasion for such praise; of all among people, it may be presumed that they will be best qualified to appreciate the goodness of the Lord.