2 Peter letter 2:21-22

because it were better for them not to have recognized the way of righteousness, than, after recognizing, themselves turn away from the holy commandment, which is handed over become to them. by them has self confirmed that true proverb: a dog has self returned to that, which he has vomited, and a washed swine self to wallow in mud! (Proverbs 26, 11)