Deuteronomy 31:24-26

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, that bare the ark of the covenant of Jehovah, saying, Take this book of the law, and put it by the side of the ark of the covenant of Jehovah your God, that it may be there for a witness against thee.