John Calvin Commentary Psalms 69:10

"When I wept, [and chastened] my soul with fasting, That was to my reproach." — Psalms 69:10 (ASV)

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, since he was not driven or inflamed by the impulsiveness of the flesh, but rather humbly humbled himself before God, choosing Him to be the witness of his sorrow.

By this he shows more clearly the incorrigible perversity of his enemies. It frequently happens that those who set themselves boldly for the defense of God’s glory provoke and exasperate the wicked to a higher degree by opposing them argumentatively and without moderation. But David’s zeal was so tempered that it ought to have softened even the hardness of steel.

By this circumstance, however, he intended to show that he was oppressed with such violence by the perversity of his enemies that he did not dare even to open his mouth to speak a single word in defense of God’s cause, and no other means were left for him to defend it but tears and mourning.

He was deprived, as we know, of the liberty of expressing the thoughts of his heart; or rather, his words, as being those of a condemned person, would have been rejected with cruel rebukes. It was a proof of greater steadfastness when, in such circumstances, he continued to burn with a zeal as undiminished as ever and persevered in the voluntary sorrow he had undertaken to exercise in order to maintain 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 signs of mourning among the Jews. But his enemies turned all these things into mockery and jesting, from which it is clear that they were carried away with demonic fury.

It is important for us to be strengthened by such an example, so that in the present day we may not be discouraged when we encounter the same perversity by which the enemies of the Gospel prove themselves to be devils rather than men.

We must, however, beware of pouring oil on the fire that is already burning too fiercely. Instead, we should imitate David and Lot, who, although they did not have the liberty to rebuke the wicked, were still deeply grieved in their hearts. And even when the wicked are compelled to hear us, mildness and humility will be a powerful means, or rather will be the best seasoning, for tempering holy zeal.

Those who interpret David as suggesting that he resigned himself to suffer punishment in the place 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 contempt.