Deuteronomy 31:19-22

19Now therefore, write down for yourselves this song and teach it to the Israelites; have them recite it, so that it may be a witness for Me against them. 20When I have brought them into the land that I swore to give their fathers, a land flowing with milk and honey, they will eat their fill and prosper. Then they will turn to other gods and worship them, and they will reject Me and break My covenant. 21And when many troubles and afflictions have come upon them, this song will testify against them, because it will not be forgotten from the lips of their descendants. For I know their inclination, even before I bring them into the land that I swore to give them.”

22So that very day Moses wrote down this song and taught it to the Israelites.