Deuteronomy 12:32 in the World English Bible
Whatever thing I command you, that you shall observe to do. You shall not add to it, nor take away from it.
Context
31 Thou shalt not do so unto the LORD thy God: for every abomination to the LORD, which he hateth, have they done unto their gods; for even their sons and their daughters they have burnt in the fire to their gods.
32 What thing soever I command you, observe to do it: thou shalt not add thereto, nor diminish from it.