2 Peter 2:20-22

Williams(i) 20 For if, after men have escaped the corrupting ways of the world through a full knowledge of the Lord and Saviour Jesus Christ, they again become entangled in them and are conquered by them, then their last condition is worse than their former one. 21 For it would have been better for them never to have known the way of uprightness than to have known it and then to turn their backs on the sacred command committed to their trust. 22 In them is verified the truth of the proverb, "A dog turns back to what he has vomited"; and of that other proverb, "A sow that has washed herself goes back to wallow in the mire."