Deuteronomy 31:21-22

And it shall come to pass, when many evils and troubles are befallen them, that this song shall testify against them as a witness; for it shall not be forgotten out of the mouths of their seed: for I know their imagination which they go about, even now, before I have brought them into the land which I sware. {against: Heb. before} {go...: Heb. do} Moses therefore wrote this song the same day, and taught it the children of Israel.