Deuteronomy 31:27

While I am yet alive - ye have been rebellious - Such was the disposition of this people to act contrary to moral goodness that Moses felt himself justified in inferring what would take place from what had already happened.

1. Never was a people more fully and faithfully warned, and from this very circumstance we may see that they were under no fatal constraining necessity to commit sin against God; they might have avoided it, but they would not. God was present to help them, till by their repeated provocations they forced him to depart: wrath therefore came upon them to the uttermost because they sinned when they might have lived to the glory of God. Those who abuse God's grace shall not only have that grace taken away from them, but shall be punished for the abuse of it, as well as for the transgression. Every sin is double, and must have a twofold punishment; for 1. Grace is resisted; 2. Transgression is committed; and God will visit for both.

2. How astonishing it is that, with such examples of God's justice before their eyes, the Jews should be so little affected; and that the Gentiles, who have received the Gospel of God, should act as if God would no more punish transgression, or that he must be so partial to them as to pass by iniquities for which the hand of his justice still continues heavy upon the descendants of Jacob! Let them take heed, for if God spared not the natural branches, he will not spare them. If they sin after the manner of the Jews, they may expect to be partakers with them in their punishments. What God does to nations he will do to individuals who reject his mercy, or trample under foot his grace; the soul that sinneth, and returns not to God by repentance and faith, shall die. This is a decree of God that shall never be reversed, and every day bears witness how strictly he keeps it in view.

3. The ode composed by Moses for this occasion was probably set to some lively and affecting air, and sung by the people. It would be much easier to keep such a song in remembrance, than an equal quantity of prose. The whole would have the additional circumstances of cadence and tune to cause it to be often repeated; and thus insure its being kept in memory. Poetry, though often, nay, generally abused, is nevertheless a gift from God, and may be employed with the best effect in his service. A very considerable part of the Old Testament is written in poetry; particularly the whole book of Psalms, great part of the prophet Isaiah, the Lamentations, and much of the minor prophets. Those who speak against poetic compositions in the service of God, speak against what they do not understand. All that a man hath should be consecrated to his Maker, and employed in his service; not only the energy of his heart and mind, the physical force of his body, but also the musical tones and modulations of his voice.

How much more after my death - Hence, Deuteronomy 31:24 and the rest of the book (with the exception of the song, Deuteronomy 31:19) must be regarded as a kind of appendix added after Moses' death by another hand; though the Blessing Deuteronomy 33 is of course to be regarded as a composition of Moses.