Deuteronomy 31:19, 21, 26

“Now write down this song and teach it to the Israelites and have them sing it, so that it may be a witness for me against them.

And when many disasters and calamities come on them, this song will testify against them, because it will not be forgotten by their descendants. I know what they are disposed to do, even before I bring them into the land I promised them on oath.”

“Take this Book of the Law and place it beside the ark of the covenant of the LORD your God. There it will remain as a witness against you.