Now it is certain that in the Law there is prescribed to men a rule by which they ought to regulate their life, so as to obtain salvation in the sight of God. That the Law can do nothing else than condemn, and is therefore called the doctrine of death, and is said by Paul to increase transgressions, (Rom. 7:13,) arises not from any fault of its doctrine, but because it is impossible for us to perform what it enjoins. Therefore, though no man is justified by the Law, yet the Law itself contains the highest righteousness, because it does not falsely hold out salvation to its followers, if any one fully observed all that it commands. Nor ought we to look upon this as a strange manner of teaching, that God first demands the righteousness of works, and next offers a gratuitous righteousness without works; for it is necessary that men should be convinced of their righteous condemnation, that they may betake themselves to the mercy of God. Accordingly, Paul (Rom. 10:5, 6) compares both kinds of righteousness, in order to inform us that the reason why we are freely justified by God is, that we have no righteousness of our own. Now Christ in this reply accommodated himself to the lawyer, and attended to the nature of his question; for he had inquired not how salvation must be sought, but by what works it must be obtained.
—John Calvin, Commentary on a Harmony of the Evangelists Matthew, Mark, and Luke, trans. William Pringle, (repr. Bellingham, WA: Logos Bible Software, 2010), 3.56–57.