Peter Pett's Commentary on the Bible
Deuteronomy 32:46,47
A Summary Of Moses' Final Activity (Deuteronomy 32:46).
A summary is now given of what was in fact Moses' final activity before his death. The song being completed Moses, together with Joshua (Hoshea is Joshua with the Yah element removed), having proclaimed the words of the song to the people, followed it up with an exhortation to keep the whole Instruction that he had given to them.
Analysis using the words of Moses:
a ‘And he said to them, Set your heart to all the words which I testify to you this day (Deuteronomy 32:46 a).
b Which you shall command your children to observe to do, even all the words of this law (Deuteronomy 32:46 b).
b For it is no vain thing for you, because it is your life (Deuteronomy 32:47 a).
a And through this thing you will prolong your days in the land, to which you go over the Jordan to possess it (Deuteronomy 32:47 b).
Note in ‘a' that they are to set their hearts to the words he has spoken that day, for in the parallel it is through those words that they will prolong their days in the land which they are going over Jordan to possess (Moses thoughts are fixed firmly on this triumph which he will never see. All his thoughts are for his people). In ‘b' they are to command their children to observe them, for they are no vain thing for them, they are life itself,
‘ And he said to them, Set your (of ye) heart to all the words which I testify to you this day, which you (ye) shall command your children to observe to do, even all the words of this law. For it is no vain thing for you, because it is your life, and through this thing you (ye) will prolong your days in the land, to which you (ye) go over the Jordan to possess it.'
In his final moments with them he calls on them to set their hearts on all the words which he has testified to them ‘this yom'. This probably means ‘at this time' rather than literally ‘this very day' (‘yom' is a time word which can refer to a period of time rather than always signifying ‘a day'). While it is possible that all this from Deuteronomy 5:1 onwards, including his speech, his secret meeting with Yahweh, and the writing of the song, had all taken place in one day, a very crowded day, especially for an old man, it is improbable. The point is rather that it was all part of his final time connected with preparing for his departure.
He stresses that they must teach these words to their children with the command that they obey them, for it is through observing these words that both they and their children will have true life, and a life that is prolonged in the land which they will shortly be crossing Jordan to possess. Compare for these words Deuteronomy 30:19. His final thought is that they face up to the issues of life.