When Moses had finished his song, which he delivered not only in the hearing of the people, but particularly of Joshua, his successor, as if that he might be a witness both for the LORD and for himself, he makes a short observation upon the whole: and as a dying pastor, again, and again, affectionately entreats them to be wise unto salvation after his departure. See a beautiful example of this kind in Paul. Acts 20:28-37.
Deuteronomy 32:40-48
40 For I lift up my hand to heaven, and say, I live for ever.
41 If I whet my glittering sword, and mine hand take hold on judgment; I will render vengeance to mine enemies, and will reward them that hate me.
42 I will make mine arrows drunk with blood, and my sword shall devour flesh; and that with the blood of the slain and of the captives, from the beginning of revenges upon the enemy.
43 Rejoice,i O ye nations, with his people: for he will avenge the blood of his servants, and will render vengeance to his adversaries, and will be merciful unto his land, and to his people.
44 And Moses came and spake all the words of this song in the ears of the people, he, and Hosheaj the son of Nun.
45 And Moses made an end of speaking all these words to all Israel:
46 And he said unto them, Set your hearts unto all the words which I testify among you this day, which ye shall command your children to observe to do, all the words of this law.
47 For it is not a vain thing for you; because it is your life: and through this thing ye shall prolong your days in the land, whither ye go over Jordan to possess it.
48 And the LORD spake unto Moses that selfsame day, saying,