John Calvin Commentary Psalms 38:5

"My wounds are loathsome and corrupt, Because of my foolishness." — Psalms 38:5 (ASV)

My wounds have become putrid. In this verse, he pleads the long continuation of his disease as an argument for obtaining some alleviation. When the Lord declares, concerning his Church,

that her warfare is accomplished, that her iniquity is pardoned,
for she has received of the Lord’s hand double for all her sins (Isaiah 40:2).

His meaning is that when he has sufficiently chastised his people, he is quickly pacified towards them. Moreover, if he continues to manifest his displeasure for too long a time, he becomes through his mercy, as it were, weary of it, so that he hastens to give deliverance, as he says in another place,

For my name’s sake will I defer my anger, and for my praise will I refrain for you, that I do not cut you off. Behold, I have refined you, but not with silver; I have chosen you in the furnace of affliction (Isaiah 48:9–10).

The object, therefore, which David has in view in complaining of the long continuance of his misery is that when he had endured the punishment which he had merited, he might at last obtain deliverance. It was certainly no slight trial to this servant of God to be thus kept in continual languishing and, as it were, to putrefy and be dissolved into corruption in his miseries.

In this, his constancy is the more to be admired, for it neither faltered due to the long period of delay nor failed under the immense load of suffering.

By using the term foolishness instead of sin, he does not seek in this way to extenuate his faults, as hypocrites do when they are unable to escape the charge of guilt. For, to excuse themselves in part, they allege the false pretense of ignorance, pleading and wishing it to be believed that they erred through imprudence and inadvertence.

But, according to a common mode of expression in the Hebrew language, by the use of the term foolishness, he acknowledges that he had been out of his right mind when he obeyed the lusts of the flesh in opposition to God.

The Spirit, by employing this term in so many places to designate the most atrocious crimes, certainly does not mean to extenuate the criminality of men, as if they were guilty merely of some slight offenses. Rather, the Spirit charges them with maniacal fury because, blinded by unhallowed desires, they willfully fly in the face of their Maker.

Accordingly, sin is always conjoined with folly or madness. It is in this sense that David speaks of his own foolishness; as if he had said that he was void of reason and transported with madness, like the infatuated rage of wild beasts, when he neglected God and followed his own lusts.