O thou enemy, destructions are come to a perpetual end: and thou hast destroyed cities; their memorial is perished with them.
O thou enemy - rather Hebrew haa'owyeeb (H341) 'as for the enemy' (see note Psalms 9:5; Psalms 9:7) Satan is the O thou enemy - rather, Hebrew, haa'owyeeb (H341), 'as for the enemy' (see note, Psalms 9:5; Psalms 9:7). Satan is the adversary, in the court of divine justice, against man. The Lord Messiah is our Advocate, and so 'rebukes' Satan (cf. Zechariah 3:1-2), "The Lord rebuke thee, O Satan: the Lord that hath chosen Jerusalem rebuke thee." Egypt, the Philistines, Babylon, Edom, Rome, and Autichrist, in various ages are the enemy's, representatives, and constitute the visible "enemy" for the time being. David probably had chiefly in view the Amalekites, who, after the victories of Saul and David over them, altogether disappear from history (2 Samuel 8:12). See how the people of God overcome the enemy, Romans 16:20; Revelation 12:11.
Destructions are come to a perpetual end - literally, 'consummated (or finished) are the wastes forever' х tamuw (H8552) chªraabowt (H2723) laanetsach (H5331)]: 'his own now desolated strongholds (parallel to 'the cities') are finished forever.' So Job 3:14, "With kings ... which built desolate places (same Hebrew as here) for themselves:" i:e., places doomed to be desolate. The Hebrew for 'to an end' is literally 'to victory' (cf. Isa. 2:58 with 1 Corinthians 15:54). "The last enemy that shall be destroyed is death (1 Corinthians 15:26; Revelation 20:14). The enemy's strongholds (2 Corinthians 10:4; Colossians 2:15) are now wastes - "come to a perpetual end."
And thou hast destroyed cities - "thou," i:e., God. Therefore, it is not likely that the "enemy" is addressed in the first clause; for then "thou" in the first clause would mean the enemy, in the second, God. God is addressed throughout the verse. Thou, O God, hast destroyed the enemy's strongholds utterly and forever.
Their memorial is perished with them - literally, 'their memorial, even it has perished:' or 'even theirs,' emphatically repeated. Here David has in view the Amalekites, who had been by this time utterly extinguished. Compare Exodus 17:14; Deuteronomy 25:19; Numbers 24:20.