Deuteronomy 31:24-26

24 When Moses had finished a writing the words of this law in a book to the very end, 25 Moses commanded b the Levites who carried the ark of the covenant of the  Lord, 26 Take this Book of the Law c and put it by the side of the ark of the covenant of the  Lord your God, that it may be there for d a witness against you.
Copyright information for ESV