What is written in the law? He receives from Christ a reply different from what he had expected. And, indeed, no other rule of a holy and righteous life was prescribed by Christ than what had been laid down by the Law of Moses; for the perfect love of God and of our neighbors comprehends the utmost perfection of righteousness. Yet it must be observed, that Christ speaks here about obtaining salvation, in agreement with the question which had been put to him; for he does not teach absolutely, as in other passages, how men may arrive at eternal life, but how they ought to live, in order to be accounted righteous in the sight of God. 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, (Romans 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. [1] 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 (Romans 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.

Footnotes

1 - "S'il s'en trouvoit quelqu'un qui observast entierement ce qu'elle commande;" -- "if any one were found who observed entirely what it commands."

What is written - Jesus referred him to the "law" as a safe rule, and asked him what was said there. The lawyer was doubtless endeavoring to justify himself by obeying the law. He trusted to his own works. To bring him off from that ground - to make him feel that it was an unsafe foundation, Jesus showed him what the law "required," and thus showed him that he needed a better righteousness than his own. This is the proper use of the law. By comparing ourselves with "that" we see our own defects, and are thus prepared to welcome a better righteousness than our own - that of the Lord Jesus Christ. Thus the law becomes a schoolmaster to lead us to him, Galatians 3:24.

What is written in the law?.... Christ, with great propriety, sends him to the law, to see and observe what was written there, what are the terms and conditions of life, as fixed there; partly, because this man, by his office and character, was an interpreter of the law; and partly, because his question was, what shall I do?
how readest thou? in the law, every day; referring to the "Keriat Shema", the reading of the Shema, i.e. those words in Deuteronomy 6:4, &c, "Hear, O Israel, &c." morning and evening (i) as appears by his answer
(i) Vid. Misn. Beracot, c. 1. sect. 1, 2.

What is written in the law--apposite question to a doctor of the law, and putting him in turn to the test [BENGEL].