Cross reference
Proverbs 26:11
11 As a dog that returneth to his vomit, `So is' a fool that repeateth his folly.
Exodus 8:15
15 But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them, as Jehovah had spoken.
2 Peter 2:22
22 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.
Matthew 12:45
45 Then goeth he, and taketh with himself seven other spirits more evil than himself, and they enter in and dwell there: and the last state of that man becometh worse than the first. Even so shall it be also unto this evil generation.