Charles H. Spurgeon on Psalms 137:7

Remember, O LORD, the, children of Edom, etc. Or all kinds of evil speaking against our brother, this sin of Edom, to sharpen an enemy against our brother in the day of his sorrow and distress, this opening of the mouth wide against him, to exult over him in his calamity, is most barbarous and unchristian. ...Observe how the cruelty of the Edomites is aggravated by this time; the most woeful time that ever Jerusalem had, called therefore the day of Jerusalem. When all things conspired to make their sorrow full, then, in the anguish and fit of their mortal disease, then did Edom arm his eye, his tongue his heart, his hand, and join all those with the enemy against his brother. Learn, that God taketh notice not only what we do against another, but when;for he will set these things in order before us; for the God of mercy cannot abide cruelty. —Edward Marbury, 1649.