John Calvin's Bible Commentary
Psalms 109:21
21And thou, O Jehovah my Lord! From the pouring out of complaints and imprecations against his enemies, the Psalmist passes to prayers; or rather, after having betaken himself to God as his guardian and deliverer, he appears to take occasion, from this circumstance, to encourage himself in prayer; even as all the pious reflections by which the faithful exercise and strengthen their faith, stimulate them to call upon the name of God. At the same time, he does not pique himself upon any service which he has rendered to God, as deserving of his help, nor does he rely upon his own worthiness, but he places all his confidence in the free grace and mercy of God. That integrity of which he was conscious, he placed in opposition to his enemies, for the purpose of making their iniquity more manifest; but he does not aspire after any recompense from God, because he adopts the nobler principle, that of owing every thing to God’s voluntary choice, upon which also he acknowledges his safety depends. Were it lawful for any one to boast of his virtues and merits, certainly David was not the man who was least entitled to do so; and, moreover, he was the representative of Christ, and of the whole Church. Hence it follows, that all our prayers will vanish in smoke, unless they are grounded upon the mercy of God. The case of Christ was indeed a peculiar one, inasmuch as it was by his own righteousness that he appeased the wrath of his Father towards us. As, however, his human nature was entirely dependant on the good pleasure of God, so it was his will, by his own example, to direct us to the same source. What can we do, seeing that the most upright among us is constrained to acknowledge that he is chargeable with the commission of much sin; surely we never can make God our debtor? It follows, therefore, that God, on account of the benignity of his nature, takes us under his protection; and that, because of the goodness of his mercy, he desires his grace may shine forth in us. In coming to God, we must always remember that we must possess the testimony of a good conscience, and must beware of harbouring the thought that we have any inherent righteousness which would render God our debtor, or that we deserve any recompense at his hands. For if, in the preservation of this short and frail life, God manifests the glory of his name and of his goodness, how much more ought all confidence in good works to be laid aside, when the subject-matter referred to is life heavenly and eternal? If, in the prolonging of my life for a short time on earth, his name is thereby glorified, by manifesting of his own accord towards me his benignity and liberality; when, therefore, having delivered me from the tyranny of Satan, he adopts me into his family, washes away my impurity in the blood of Christ, regenerates me by his Holy Spirit, unites me to his Son, and conducts me to the life of heaven, — then, assuredly, the more bountifully he treats me, the less should I be disposed to arrogate to myself any portion of the praise. How different a part does David act, who, in order to procure favor for himself, publishes his own poverty and misery? And as outward affliction is of no avail, unless a man, at the same time, be humbled, and his proud and rebellious spirit be subdued, the Psalmist here repeats, that his heart was wounded within him. From which we may learn, that God will be a physician to none, except to such as in the spirit of genuine humility send up their sighs and groans to him, and do not become hardened under their afflictions.