Matthew Henry's Complete Bible Commentary
Verses 17—18
Here, 1. The pleasure we are apt to take in the troubles of an enemy is forbidden us. If any have done us an ill turn, or if we bear them ill-will only because they stand in our light or in our way, when any damage comes to them (suppose they fall), or any danger (suppose they stumble), our corrupt hearts are too apt to conceive a secret delight and satisfaction in it—Aha! so would we have it; they are entangled; the wilderness has shut them in—or, as Tyrus said concerning Jerusalem (Ezekiel 26:2) I shall be replenished, now she is laid waste. “Men hope in the ruin of their enemies or rivals to wreak their revenge or to find their account; but be not thou so inhuman; rejoice not when the worst enemy thou hast falls.” There may be a holy joy in the destruction of God’s enemies, as it tends to the glory of God and the welfare of the church (Psalms 58:10); but in the ruin of our enemies, as such, we must by no means rejoice; on the contrary, we must weep even with them when they weep (as David, Psalms 35:13, 35:14), and that in sincerity, not so much as letting our hearts be secretly glad at their calamities. 2. The provocation which that pleasure gives to God is assigned as the reason of that prohibition: The Lord will see it, though it be hidden in the heart only, and it will displease him, as it will displease a prudent father to see one child triumph in the correction of another, which he ought to tremble at, and take warning by, not knowing how soon it may be his own case, he having so often deserved it. Solomon adds an argument ad hominem—addressed to the individual: “Thou canst not do a greater kindness to thy enemy, when he has fallen, than to rejoice in it; for them, to cross thee and vex thee, God will turn his wrath from him; for, as the wrath of man works not the righteousness of God, so the righteousness of God was never intended to gratify the wrath of man, and humour his foolish passions; rather than seem to do that he will adjourn the execution of his wrath: nay, it is implied that when he turns his wrath from him he will turn it against thee and the cup of trembling shall be put into thy hand.” MHBCC 653.8