As a dog returns to his vomit, so a fool returns to his folly.
All Commentaries on Proverbs 26:11 Go To Proverbs 26
John Chrysostom
AD 407
Don’t you know that people so unconcerned about their own salvation and vacillating between attention to it and headlong course into the devil’s net are compared in sacred Scripture with dogs? It says, remember, “The person who turns away from his sin and then goes back to it is like a dog returning to its vomit.”