Deuteronomy 31:19, 21, 26

“Now therefore write this song and teach it to the people of Israel. Put it in their mouths, that this song may be a witness for me against the people of Israel.

And when many evils and troubles have come upon them, this song shall confront them as a witness (for it will live unforgotten in the mouths of their offspring). For I know what they are inclined to do even today, before I have brought them into the land that I swore to give.”

“Take this Book of the Law and put it by the side of the ark of the covenant of the LORD your God, that it may be there for a witness against you.