Revenge is a double-edged sword

This everyday expression means that if a person takes their revenge, the consequences could backfire on that person at a later stage.
The expression is a metaphor that may be derived from one of Aesop's Fables, ‘The Farmer and the Fox’. Aesop lived between c. 620-560 BCE.

A Farmer was plagued by a Fox who regularly stole his chickens.
He decided to lay a trap and catch him, which he succeeded in doing.
To punish the Fox, he attached an oily cloth to his tail, set fire to it and released him.
The Fox ran off into the Farmer’s cornfields and set them all ablaze, ruining his crop.
The moral of the story is that revenge can hurt the attacker in the same way as a double edged sword can hurt the person wielding it.