And thou shalt put into the ark the testimony which I shall give thee. (25:16)

--Deuteronomy--

And Moses wrote this law, and delivered it unto the priests the sons of Levi, which bare the ark of the covenant of the Lord, and unto all the elders of Israel. (31:9)

Take this book of the law, and put it in the side of the ark of the covenant of the Lord your God, that it may be there for a witness against thee. (31:26)