- 1611, King James Version of the Bible, Book of Proverbs, 26:11
- As a dog returneth to his vomit, so a fool returneth to his folly.
Originally from Hebrew:
- ככלב שב על־קאו כסיל שונה באולתו׃
as a dog returns to his vomit, so a fool repeats his folly
- Foolish people repeatedly do foolish things.