Deuteronomy 31:9

9.And Moses wrote this law. It is unquestionable that Moses deposited the Book of the Law in the custody of the Levites, to enjoin upon them the duty of teaching; for although it is only related that they were commanded to recite the book before the people every seventh year, yet it is easy to gather that they were appointed the constant proclaimers of its doctrine. For it would have been absurd that the Law should lie buried for seven whole years, and that not a word should be heard of its instruction; besides, the difficulty of hearing in so great a multitude would be great, and the recollection of it would soon have vanished. In a word, very little would have been the use of the ceremony, if at all other times the Levites had been dumb, and nothing should have been heard throughout the land regarding the worship of God. This then was the object of the solemn promulgation of the Law, (Deuteronomy 31:10, etc.), which was made in the year of release, that the people should daily inquire the right way of serving God of the Levites, who were chosen to be as it were νομοφύλακες (guardians of the Law), that they might bring forward in due season whatever it was profitable to know. Here, then, is represented to us as in a mirror what Paul says, that the Church of God is “the pillar and ground of the truth,” (1 Timothy 3:15;) because purity of doctrine is preserved unimpaired in the world, and propagated by the ministry of pastors, whilst piety would soon decay if the living preaching of doctrine should cease. Therefore Paul also elsewhere commands that the sound doctrine, of which he was a minister, should be committed by Timothy

"to faithful men, who should be able to teach others also.”
(2 Timothy 2:2.)

First, then, we must remember, that the Book of the Law was given in trust, as it were, to the Levites, that the people might learn from them what was right. The addition of “the elders” is not superfluous; for although the office of teaching was not committed to them, yet were they given as coadjutors to the Levites, in order that they might uphold the doctrine of the Law, and not suffer it to be scorned. We know how great is the insolence of the people in rejecting pious teachers, unless they are restrained by those in authority; nor do the latter indeed duly fulfill their duty, if they do not keep their subjects to the study of religion, who would be otherwise too much disposed to impiety.

Moses in this passage calls by the name of “the Law,” not the Ten Commandments engraved on the two tables, but the interpretation of it contained in the four books. The circumstances took place thirty-nine years after God had spoken on Mount Sinai. What follows, that it was to be read every seven years, I have commented on elsewhere; (187) but there will be no harm in repeating what may serve for the understanding of this passage. The seventh year was chosen for this purpose, because all, both males and females, might then assemble at Jerusalem without detriment to their private interests, for there was a cessation from all labor; they neither sowed, nor reaped, and agriculture was altogether at a stand-still. There was therefore no business to prevent them from celebrating that festival, whereby God represented to them in a lively manner, how miraculously He had preserved their fathers in the desert. Lest the recollection of so great a benefit should ever perish, the Law indeed commanded them, wherever they might be, to go forth from their houses every year, and to pass seven days under the boughs of trees; but in the Sabbatical Year, when all was at rest at home, it was more convenient for them to go up to Jerusalem from all quarters, that by their very multitude they might the better testify their gratitude. Therefore it is added, “when all Israel is come,” etc. And it must be observed, that in that assembly they were more solemnly pledged, one and all, to keep the Law, because they were mutually witnesses against each other if they should break the covenant thus publicly renewed. On this account it is added, “Gather the people together, men, women, and children.” But that it might not be a mere empty spectacle, it is expressly commanded that the book should be read “in their hearing:” by which words a recitation is expressed, from whence the hearers might receive profit, else it would have been a sham and ludicrous parade; just as in the Papacy, when they loudly bellow out the Scriptures in an unknown tongue, they do but profane God’s name. To this end, therefore, did God desire the doctrine of His Law to be heard; viz., that He might obtain disciples for Himself; not that He might fill their ears with a senseless and unprofitable clamour. And indeed when the Popish priests were a little ashamed of altogether driving the people away from hearing God’s word, they devised this foolish plan of shouting to the deaf, as if this silly formality would satisfy God’s command, when He ordains that all should be taught from the least to the greatest: for it is afterwards again expressed, “that they may hear, and that they may learn.” Hence we lay it down, that the legitimate use of Scripture is perverted when it is enunciated in an obscure manner such as no one can understand. But whilst no other mode of reading Scripture is approved by God, except such as may instruct the people, so also the fruit of understanding, i.e., that they may learn to fear God, is required in the hearers. But it is undoubted, that “the fear of God” comprehends faith, nay, that properly speaking it springs from faith; and by this expression Moses indicates that the Law was given for the purpose of instructing men in piety and the pure service of God. At the same time we may learn from this passage, that all the services which are paid to God in ignorance, are extravagant, and illegitimate. The beginning of wisdom is to fear God; and on this point all agree; but then each one slips away to his own imaginations and erroneous devotions, as they choose to call them. God, however, in order to restrain such audacity as this, declares that he is not duly worshipped, except He shall first have been listened to. As to “the strangers,” when their participation in sacred things is in question, I have elsewhere observed that all foreigners are not so called, but only those who, being Gentiles by origin, had devoted themselves to God, and having received circumcision, had been incorporated into the Church; otherwise it would not have been lawful to admit them into the congregation of the faithful; and this is confirmed by the additional words, “that is within thy gates:” which is as much as if Moses had said, inhabitants of your cities, and dwelling together with the people. Finally, when their children are mentioned, reference is made to the propagation of sound doctrine, that the pure worship of God may continually be maintained. He therefore commands that the Law should be recited, not in one generation only, but as long as the status of the people may last; and surely all God’s servants ought to take care, that they may transmit to posterity what they have learnt themselves. Yet we must remark, that all doctrine which may have been handed down from their ancestors, is not here promiscuously commended; but God rather claims for Himself the entire authority, both towards the fathers and the children.