{c} O thou enemy, destructions are come to a perpetual end: and thou hast destroyed cities; their memorial is perished with them.

(c) A derision of the enemy that minds nothing but destruction: but the Lord will deliver his, and bring him into judgment.

King James Translators' Notes

O thou...: or, The destructions of the enemy are come to a perpetual end: and their cities hast thou destroyed, etc

Jamieson-Fausset-Brown Bible Commentary

6. Literally, "As to the enemy finished are his ruins for ever. Thou [God] hast destroyed," &c. (1Sa 15:3, 7; 27:8, 9). The wicked are utterly undone. Their ruins shall never be repaired.

Matthew Henry's Concise Commentary

9:1-10 If we would praise God acceptably, we must praise him in sincerity, with our whole heart. When we give thanks for some one particular mercy, we should remember former mercies. Our joy must not be in the gift, so much as in the Giver. The triumphs of the Redeemer ought to be the triumphs of the redeemed. The almighty power of God is that which the strongest and stoutest of his enemies are no way able to stand before. We are sure that the judgment of God is according to truth, and that with him there is no unrighteousness. His people may, by faith, flee to him as their Refuge, and may depend on his power and promise for their safety, so that no real hurt shall be done to them. Those who know him to be a God of truth and faithfulness, will rejoice in his word of promise, and rest upon that. Those who know him to be an everlasting Father, will trust him with their souls as their main care, and trust in him at all times, even to the end; and by constant care seek to approve themselves to him in the whole course of their lives. Who is there that would not seek him, who never hath forsaken those that seek Him?