2 Peter 2:20-22

When new believers escape the corruption of the world through knowing our LORD and SAVIOR JESUS CHRIST, and then if they become entangled in it again and overcome, they are worse off at the end than they were at the beginning. For it would have been better for them to have never known the way of righteousness, than to have known it and then to reject the holy commandments given to them. For them, these proverbs have come true: "A dog returns to its own vomit," and "After washing, a sow returns to wallowing in the mud."