Can you point to any part of the Constitution that says that?
When officers of government, all of them, take their oath, as required by Article VI, they swear to support and defend the Constitution. All of it.
The world is full of things and truths that are not mentioned in the Constitution. It’s a Constitution, not an encyclopedia.
All you have to do is READ the Preamble.
Point to something in the Preamble that commands anyone to DO SOMETHING.
You can’t. It’s not there.
Therefore, the Preamble is not law.