'Know the Truth' in the Bible

Then I would know the truth of the fourth beast, which was diverse from all the others, exceedingly dreadful, whose teeth were of iron, and its nails of bronze; which devoured, broke in pieces, and stamped the residue with its feet;

And you shall know the truth, and the truth shall make you free.

Forbidding to marry, and commanding to abstain from foods, which God has created to be received with thanksgiving of them who believe and know the truth.