Psalms 7:10

"My righteous help is from the Lord, who maketh whole the upright in heart" (ver. 10). The offices of medicine are twofold, on the curing infirmity, the other the preserving health. According to the first it was said in the preceding Psalm, "Have mercy on me, O Lord, for I am weak;" according to the second it is said in this Psalm, "If there be iniquity in my hands, if I have repaid them that recompense me evil, may I therefore fall by my enemies empty." For there the weak prays that he may be delivered, here one already whole that he may not change for the worse. According to the one it is there said, "Make me whole for Thy mercy's sake;" according to this other it is here said, "Judge me, O Lord, according to my righteousness." For there he asks for a remedy to escape from disease; but here for protection from falling into disease. According to the former it is said, "Make me whole, O Lord, according to Thy mercy:" according to the latter it is said, "My righteous help is from the Lord, who maketh whole the upright in heart." Both the one and the other maketh men whole; but the former removes them from sickness into health, the latter preserves them in this health. Therefore there the help is merciful, because the sinner hath no desert, who as yet longeth to be justified, "believing on Him who justifieth the ungodly;" but here the help is righteous, because it is given to one already righteous. Let the sinner then who said, "I am weak," say in the first place, "Make me whole, O Lord, for Thy mercy's sake;" and here let the righteous man, who said, "If I have repaid them that recompense me evil," say, "My righteous help is from the Lord, who maketh whole the upright in heart." For if he sets forth the medicine, by which we may be healed when weak, how much more that by which we may be kept in health. […]

That same adversary, Absalom, as if he has been born again from ourselves, prepares the war against us. Our sound judgment concerning the matter, or rather our alliance with God, turns him who is bloodthirsty against us back. For because he attributes the cause of the good things that have been accomplished for him through "the words of Cush" to God, he composes this thanksgiving.… It would be worthwhile to apply the figures of the story to the virtuous life, how the advice that saves us becomes the strangling of the adversary; and this saving advice has been recorded, on the one hand, in the history, and on the other, in the psalm.

Then he infers, "My just help is from the Lord," etc. Here the confidence conceived from the judge is set forth, from whom help is to be hoped for. For there is a twofold help of God: namely, of mercy, and another of justice. The …

My defence is of God,....

God is a righteous Judge (so some read it), who not only doeth righteousness himself, but will take care that righteousness be done by the children of men and will avenge and punish all unrighteousness. He is no less confident of the destruction of all his persecutors, even as many of them as would not repent, to give glory to God.