Moses turns next to the priests and the elders, and to them he commits the Law which he had written, with the injunction to read it to the people at the end of every seven years during the festival of the year of release, viz.
at the Feast of Tabernacles (cf. Leviticus 23:34), when they appeared before the Lord. At the end of every seven years (cf. Deuteronomy 15:1). The Law was committed to the priests and elders, not merely to preserve it in safe keeping, but that they might see to its being observed by the people; else why commit it to the elders whose it was to administer rule in the nation, as well as to the priests who alone had access to the ark of the covenant where the Law was deposited?
Moses "entrusted the reading to the priesthood and the college of elders, as the spiritual and secular rulers of the congregation; and hence the singular, Thou shalt read this Law to all Israel" (Keil).
By the Law here is meant the Pentateuch; but it does not necessarily follow that the whole of the Pentateuch was to be thus read. As the reading was to be only once in seven years, it may be concluded that it was not so much for the information of the people that this was done, as for the purpose of publicly declaring, and by a solemn ceremony impressing on their minds the condition on which they held their position and privileges as the chosen people of the Lord; and for this the reading of select portions of the Torah would be sufficient.
The Feast of Tabernacles was appointed as the season for the reading, doubtless because there was a connection between the end for which the Law was read and the spirit and meaning of that festival as a festival of rejoicing because of their deliverance from the uncertainty and unsettledness of their state in the wilderness, and their establishment in a well-ordered state where they could in peace and quietness enjoy the blessings which the bounty of God bestowed.
When all Israel is come to appear before the Lord (cf. Deuteronomy 16:16). Thou shalt read this law (cf. Joshua 8:34; 2 Kings 23:2; Nehemiah 8:1, etc.).