Arthur Schopenhauer said this quote

To free a man from error is not to deprive him of anything but to give him something: for the knowledge that a thing is false is a piece of truth. No error is harmless: sooner or later it will bring misfortune to him who harbours it. Therefore deceive no one, but rather confess ignorance of what you do not know, and leave each man to devise his own articles of faith for himself.