3 “Why does he glory in malice that is mighty?”. Observe, my brethren, the glorying of malignity, the glorying of evil men. Where is glorying? “Why does he glory in malice that is mighty?” That is, he that in malice is mighty, why does he glory? There is need that a man be mighty, but in goodness, not in malice. Is it any great thing to glory in malice? To build a house does belong to few men, any ignorant man you please can pull down. To sow wheat, to dress the crop, to wait until it ripen, and in that fruit on which one has laboured to rejoice, does belong to few men: with one spark any man you please can burn all the crop.
To breed an infant, when born to feed him, to educate, to bring him on to youth's estate, is a great task: to kill him in one moment of time any one you please is able. Therefore those things which are done for destruction, are most easily done. “He that glories, let him glory in the Lord:” he that glories, let him glory in goodness. Thou gloriest, because you are mighty in evil. What are you about to do, O mighty man, what are you about to do, boasting yourself much? You are about to kill a man: this thing also a scorpion, this also one fever, this also a poisonous fungus can do.
To this is your mightiness reduced, that it be made equal to a poisonous fungus? This therefore do the good citizens of Jerusalem, who not in malice but in goodness glory: firstly, that not in themselves, but in the Lord they glory. Secondly, that those things which make for edification they earnestly do, and do such things as are strong to abide: but things which make for destruction they may do, for the discipline of men advancing, not for the oppression of the innocent. To this mightiness then that earthly body being compared, why may it not hear out of these words, “Why does he glory in malice that is mighty?”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)