(21) This song . . . shall not be forgotten out of the mouths of their seed.--And it is not forgotten now. St. Paul made special use of it in the last days of the second Temple. This song is a favourite piece of Hebrew poetry to this day. Rashi observes: "This is a promise to Israel that the law shall not be utterly forgotten by their seed."

I know their imagination.--Heb., yetzer, the same word employed in Genesis 6:5; Genesis 8:21. It is the word commonly used in Rabbinical literature for the evil nature or good nature in any man. The nature which they are forming, or making, this day, would be a literal rendering of the sentence in this verse. And yet with all this, He made Balaam say, "He hath not beheld iniquity in Jacob nor seen perverseness in Israel" (Numbers 23:21). Comp. 1Chronicles 28:9, "The Lord . . . understandeth all the imaginations of the thoughts," and Psalm 103:14, "He knoweth our frame (yetzer); He remembereth that we are dust."

31:14-22 Moses and Joshua attended the Divine Majesty at the door of the tabernacle. Moses is told again that he must shortly die; even those who are most ready and willing to die, need to be often reminded of its coming. The Lord tells Moses, that, after his death, the covenant he had taken so much pains to make between Israel and their God, would certainly be broken. Israel would forsake Him; then God would forsake Israel. Justly does he cast those off who so unjustly cast him off. Moses is directed to deliver them a song, which should remain a standing testimony for God, as faithful to them in giving them warning, and against them, as persons false to themselves in not taking the warning. The word of God is a discerner of the thoughts and intents of men's hearts, and meets them by reproofs and correction. Ministers who preach the word, know not the imaginations of men; but God, whose word it is, knows perfectly.And it shall come to pass, when many evils and troubles are befallen them,.... As did in the times of the judges, in the Babylonish captivity, and do now in their present exile:

that this song shall testify against them as a witness; which so clearly points at their sins, with all their aggravated circumstances, and describes so fully their calamities, distresses, and punishment for them:

for it shall not be forgotten out of the mouths of their seed; which shows that it respects time to come, their later posterity, whose memory of this song would be conjured up by the evils that should come upon them for their sins; nor is it forgotten by them to this day, who acknowledge there are some things in it now fulfilled or fulfilling in them:

for I know their imagination which they go about even now: or are "making" (c); forming and framing within themselves, there being a secret inclination in their minds to idolatry, which were working and contriving schemes to bring it about, and set it up; and this, God, the searcher of hearts, knew full well, and that in process of time this evil imagination would break forth into act, in an open and flagrant manner:

before I have brought thee into the land which I sware; to their fathers, to give it to them for an inheritance, as is suggested in Deuteronomy 31:20.

(c) "faciens", Montanus; "quam facit", Pagninus.