19. Now therefore write ye this song—National songs take deep hold of the memories and have a powerful influence in stirring the deepest feelings of a people. In accordance with this principle in human nature, a song was ordered to be composed by Moses, doubtless under divine inspiration, which was to be learnt by the Israelites themselves and to be taught to their children in every age, embodying the substance of the preceding addresses, and of a strain well suited to inspire the popular mind with a strong sense of God's favor to their nation.

     16-22. the Lord said unto Moses, . . . this people will rise up—In this remarkable interview, Moses was distinctly apprised of the infidelity of Israel, their corruptions of the true religion through intercourse with the idolatrous inhabitants of Canaan (Am 5:26), and their chastisements in consequence of those national defections.

     26. Take this book of the law, and put it in the side of the ark—The second copy of the law (see on De 31:9) was deposited for greater security and reverence in a little chest beside the ark of the covenant, for there was nothing contained within it but the tables of stone (1Ki 8:9). Others think it was put within the ark, it being certain, from the testimony of Paul (Heb 9:4), that there were once other things inside the ark, and that this was the copy found in the time of Josiah (2Ki 22:8).