Amos 5:9 - Albert Barnes' Notes on the Bible

That strengtheneth the spoiled - (Literally, “spoil” English margin) probably That “maketh devastation to smile on the strong.” . The “smile,” in anger, attests both the extremity of anger, and the consciousness of the ease, wherewith the offence can be punished. They were strong in their own strength; strong, as they deemed, in their “fortress” ; “strong with an evil strength, like one phrensied against his physician.” But their strength would be weakness. “Desolation” when God willed, would “smile at” all which they accounted “might,” and would “come against the fortress,” which, as they deemed, “cut off” all approach.