Charles H. Spurgeon on Psalms 137:7

Edom's hatred was the hatred with which the carnal mind in its natural enmity against God always regards whatever is the elect object of his favour. Jerusalem was the city of God. "Rase it, rase it even to the ground", is the mischievous desire of every unregenerate mind against every building that rests on the elect Stone of Divine foundation. For God's election never pleases man until, through grace, his own heart has become an adoring receiver of that mercy which while in his natural state he angrily resented and refused to own in its effects on other men From Cain to Antichrist this solemn truth holds always, good. —Arthur Pridham.

Verses 7-9. I do not know if the same feeling has occurred to others, but I have often wished the latter verses of this Psalm had been disjoined from this sweet and touching beginning. It sounds as if one of the strings on their well tuned harps was out of melody, as if it struck a jarring note of discord. And yet I know the feeling is wrong, for it is no more than what the Lord himself had foretold and declared should be the final desolation of proud Babylon itself: yet one longs more intensely for the period when the nations of the earth shall learn war no more; and every harp and every voice, even those of the martyred ones beneath God's altar loudest and sweetest of all, shall sing the Lord's songs, the song of Moses, and the Lamb, in that pleasant land, where no sighing and no tears are seen. —Barton Bouchier.