Deuteronomy 31:26, commentary and pictures

The verse belongs to Moses' earnest, impressive final address to Israel before his death in Moab, spoken as he knew it was his last opportunity to address them. The book in view is what Moses himself wrote, containing all the laws, judgments, and statutes God had given him, along with the various regulations respecting sacrificial offerings, that is, the ceremonial laws first given at Sinai. Beyond the laws he faithfully recorded in it all the instructions given to Israel by the way, all the miracles performed for them, and all the murmurings of the children of Israel, including his own being overcome in consequence of their murmurings.

It is not a new revelation but a repetition and enlargement of those former laws, giving methods for enforcement, explaining the precepts, making plain the reasons they were given, and repeating commands that had been broken when God's judgments fell, so that transgressors would know that disobedience will surely bring God's punishment. Moses placed the book in the hands of men in the sacred office, appointed officers, with the request that for safekeeping it be put in the side of, or beside, the ark of the covenant, for God's care was continually upon that sacred chest. The written law, including writings given through Moses and statements in sacred history concerning the giving of the law at Sinai, was to be carefully preserved as God's command in that most sacred place for future reference.

Its preservation was that the judges of Israel might refer to it and consult it whenever any case should come up to make it necessary, because an erring people often understand or twist God's requirements to suit their own case and desires. Placed beside the ark to be there for a witness against Israel, the temple copy of this law was lost through neglect during Manasseh's reign, leaving the people without its instruction for many years, and its later discovery and study helped bring about Josiah's reform.