2 Peter 2:22

What has happened to them shows the truth of the proverb, "A dog returns to what he has vomited up, and a sow that has washed goes back to wallow in the mire."

Matthew 12:45

Then it goes and gets seven other spirits more wicked than itself, and they go in and live there, and in the end the man is worse off than he was before. That is the way it will be with this present wicked age."

Treasury of Scripture Knowledge

Summary

As a dog returneth to his vomit, so a fool returneth to his folly.

Bible References

A dog

Matthew 12:45
Then it goes and gets seven other spirits more wicked than itself, and they go in and live there, and in the end the man is worse off than he was before. That is the way it will be with this present wicked age."
2 Peter 2:22
What has happened to them shows the truth of the proverb, "A dog returns to what he has vomited up, and a sow that has washed goes back to wallow in the mire."