Psalms 69:10-12

10. And I wept, my soul fasted David here proves, by the signs or effects, that his efforts to promote the Divine glory proceeded from a pure and well-regulated zeal, inasmuch as he was not impelled or inflamed by the impetuosity of the flesh, but rather humbly abased himself before God, choosing him to be the witness of his sorrow. By this he shows the more evidently the incorrigible perversity of his enemies. It frequently happens, that those who set themselves boldly for the vindication of the glory of God, provoke and exasperate the wicked to a higher pitch by opposing them contentiously and without moderation. But David’s zeal was so tempered that it ought to have softened even the hardness of steel. By this circumstance he, however, intended to show that he was oppressed with such violence by the frowardness of his enemies, that he dared not even open his mouth to speak a single word in defense of the cause of God, and no other means were left him of defending it but tears and mourning. He was deprived, as we know, of the liberty of giving utterance to the sentiments of his heart, or rather his words, as being those of a condemned person, would have been repelled with cruel reproaches. It was a proof of the greater constancy when in such circumstances he continued to burn with a zeal as unabated as ever, and persevered in the voluntary sorrow which he had engaged to exercise with the view of maintaining the honor and glory of God. He accordingly declares, that he wept and that his soul fasted, and that he was clothed with sackcloth; which were the tokens of mourning among the Jews. But his enemies turned all these things into mockery and jesting; from which it is manifest that they were carried away with the fury of demons. It is of importance for us to be fortified with such an example, that in the present day we may not be discouraged when we meet with the same perversity by which the enemies of the Gospel prove themselves to be rather devils than men. We must, however, beware of pouring oil upon the fire which is already burning too fiercely, and should rather imitate David and Lot, who, although they had not liberty to rebuke the wicked, were yet deeply grieved in their hearts. And even when the wicked are constrained to hear us, mildness and humility will be a powerful means, or rather will be the best seasoning, for tempering holy zeal. Those who conceive of David as intimating that he resigned himself to suffer punishment in the room or stead of his enemies, attempt to confirm their opinion from his having clothed himself in sackcloth. But I take it more simply as meaning, that when he saw things in such a state of confusion, he voluntarily engaged in this sorrowful exercise to testify that nothing was more grievous to him than to witness the sacred name of God exposed to contumely.