Augustine of Hippo

..."For the arms of the wicked shall be broken" (ver. 17). Now by "their arms" is meant their power. What will he do in hell? Will it be what the rich man had to do, he who was wont "to fare sumptuously" in the upper world, and in hell "was tormented"? Therefore their arms shall be broken; "but the Lord upholdeth the righteous." How does He "uphold" them? What saith He unto them? Even what is said in another Psalm, "Wait on the Lord, be of good courage; and let thine heart be strengthened. …

Exposition on Psalm 37 ↗

Ambrose of Milan

For the arms, he says, of the sinners will be broken. So that their actions cannot bring any impediment to the righteous; so that the rod of the sinners is not left over the lot of the righteous. And Paul says: May God crush Satan under your feet (Rom. XVI, 20). For if his arm has been broken, he himself will be completely crushed, and his comments will be trampled upon, like the venom of a serpent. But the Lord strengthens the righteous, with the arm of the adversary broken. …

Commentaries on the Twelve Davidic Psalms ↗

Thomas Aquinas

Then when he says, "For," he proves that it is better. The reason for this is threefold. First, from the perspective of durability. Second, of usefulness, at "He will borrow." Third, of virtue, at "The mouth of the just." Regarding the first, he does two things. First, he proposes the crushing of the wicked. Second, the stability of the good. He says therefore, "For the arms," etc. As if to say: therefore the few goods of the just are better than the many goods of the wicked, because they are stable, while the others are not. …

Exposition on the Psalms of David ↗