Charles H. Spurgeon on Psalms 137:8

He that sows evil shall reap evil; he that soweth the evil of sin, shall reap the evil of punishment. So Eliphaz told Job that he had seen (Job 4:8), "they that plough iniquity, and sow wickedness, reap the same." And that either in kind or quality, proportion or quantity. In kind, the very same that he did to others shall be done to him; or in proportion, a measure answerable to it. So he shall reap what he hath sown, in quality or in quantity; either in portion the same, or in proportion the like. The prophet cursing Edom and Babel saith thus, "O daughter of Zion, happy shall he be that rewardeth thee as thou hast served us." The original is, "that recompenses to thee thy deed which thou didst to us." ...Thus is wickedness recompensed suo genere, in its own kind. So often the transgressor is against the transgressor, the thief robs the thief, proditoros proditor;as in Rome many unchristened emperors, and many christened popes, by blood and treason got the sovereignty, and by blood and treason lost it. Evil men drink of their own brewing, are scourged with their own rod, drowned in the pit which they digged for others, as Haman was hanged on his own gallows, Perillus tormented in his own engine! —Thomas Adams.

Verses 8-9. The subject of these two verses is the same with that of many chapters in Isaiah and Jeremiah; namely, the vengeance of heaven executed upon Babylon by Cyrus, raised up to be king of the Medes and Persians, united under him for that purpose. The meaning of the words, "Happy shall he be, "is, He shall go on and prosper, for the Lord of hosts shall go with him, and fight his battles against the enemy and oppressor of his people, empowering him to recompense upon the Chaldeans the works of their hands, and to reward them as they served Israel. —George Horne.

Verses 8-9. It needs no record to tell us that, in the siege and carrying away of Jerusalem, great atrocities were committed by the conquerors. We may be sure that

"Many a chiding mother then

And newborn baby died," for the wars of the old world were always attended by such barbarous cruelties. The apostrophe of Ps 137:8-9, consequently merely proclaims the certainty of a just retribution —of the same retribution that the prophets had foretold (Isa 13:16 47:1-15 Jer 50:46; compare, "who art to be destroyed", Ps 137:8), and the happiness of those who should be its ministers; who should mete out to her what she had measured to the conquered Jew. It was the decree of Heaven that their "children" should "be dashed to pieces before their eyes." The Psalmist simply recognizes the decree as just and salutary; he pronounces the terrible vengeance to have been deserved. To charge him with vindictiveness, therefore, is to impugn the justice and mercy of the Most High. And there is nothing to sustain the charge, for his words are simply a prediction, like that of the prophet. "As thou hast done, it shall be done unto thee; thy reward shall return upon thine own head": Ob 1:15. —Joseph Hammond, in "The Expositor," 1876.