2 Peter 2:20-22

For if, after they have escaped the defilements of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein and overcome, the last state is become worse with them than the first. For it were better for them not to have known the way of righteousness, than, after knowing it, to turn back from the holy commandment delivered unto them. It has happened unto them according to the true proverb, The dog turning to his own vomit again, and the sow that had washed to wallowing in the mire.