Deuteronomy 31:19, 21, 26

“Now then, write this song for yourselves, and teach it to the sons of Israel; put it in their mouth, so that this song may be a witness for Me against the sons of Israel.

Then it shall come about, when many evils and troubles have come on them, that this [sacred] song will confront them as a witness; for it will not be forgotten from the mouth of their descendants. For I know their inclination which is developing even now, before I bring them into the land which I have sworn to give them.”

“Take this Book of the Law and put it beside the ark of the covenant of the LORD your God, so that it may remain there as a witness against you.