Deuteronomy 31:23 (KJV)

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.

Moses therefore wrote this song the same day, and taught it the children of Israel.

And he gave Joshua the son of Nun a charge, and said, Be strong and of a good courage: for thou shalt bring the children of Israel into the land which I sware unto them: and I will be with thee.

And it came to pass, when Moses had made an end of writing the words of this law in a book, until they were finished,

That Moses commanded the Levites, which bare the ark of the covenant of the Lord, saying,