19 “Now therefore write this song for yourselves, and teach it to the children of Israel: put it in their mouths, that this song may be a witness for me against the children of Israel. 20 For when I shall have brought them into the land which I swore to their fathers, flowing with milk and honey, and they shall have eaten and filled themselves, and grown fat; then will they turn to other gods, and serve them, and despise me, and break my covenant. 21 It shall happen, when many evils and troubles are come on them, that this song shall testify before them as a witness; for it shall not be forgotten out of the mouths of their seed: for I know their imagination which they frame this day, before I have brought them into the land which I swore.”
22 So Moses wrote this song the same day, and taught it the children of Israel.
Matthew Henry's Commentary on Deuteronomy 31:19-22
Commentary on Deuteronomy 31:14-22
(Read Deuteronomy 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.