19 Now therefore write this song, and teach it to the Israelites; put it in their mouths, in order that this song may be a witness for me against the Israelites. 20 For when I have brought them into the land flowing with milk and honey, which I promised on oath to their ancestors, and they have eaten their fill and grown fat, they will turn to other gods and serve them, despising me and breaking my covenant. 21 And when many terrible troubles come upon them, this song will confront them as a witness, because it will not be lost from the mouths of their descendants. For I know what they are inclined to do even now, before I have brought them into the land that I promised them on oath."
22 That very day Moses wrote this song and taught it to the Israelites.
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.