John Calvin Commentary Deuteronomy 4:1

"And now, O Israel, hearken unto the statutes and unto the ordinances, which I teach you, to do them; that ye may live, and go in and possess the land which Jehovah, the God of your fathers, giveth you." — Deuteronomy 4:1 (ASV)

Now, therefore, hearken, O Israel. He requires the people to be teachable, so that they may learn to serve God, for the beginning of a good and upright life is to know what is pleasing to God.

Thus, Moses begins by commanding them to be attentive in seeking direction from the Law. He then admonishes them to prove by their whole life that they have duly profited in the Law. The promise inserted here only invites them to unreserved obedience through hope of the inheritance.

The main point is that they should neither add to nor diminish from the pure doctrine of the Law. This cannot be the case unless people first renounce their own private opinions and then shut their ears against all the speculations of others. For no one is to be regarded as a (true) disciple of the Law except those who obtain their wisdom from it alone.

It is, therefore, as if God commanded them to be content with His precepts; because in no other way would they keep His law, except by giving themselves wholly to its teaching. Consequently, only those who depend on His authority alone obey God, and only those who receive nothing opposed to its natural meaning pay the Law its rightful honor. This passage is a remarkable one, openly condemning whatever human ingenuity may invent for the service of God.