an eye for an eye, a tooth for a tooth

proverb Compensation or retribution that is (or should be) of an equal amount or degree to the injury or offense that was originally dealt. The saying comes from various passages in the Bible, including in Exodus, Leviticus, and Deuteronomy. I cannot be placated by paltry excuses of reparation! An eye for an eye, a tooth for a tooth—this I demand from all who have wronged me. Some countries have laws that punish crimes with an eye for an eye, most often that killing someone will result in one's death. The world would be a safer place if more people in power would discourage the practice of an eye for an eye, a tooth for a tooth.

an eye for an eye and a tooth for a tooth

used to refer to the belief that retaliation in kind is the appropriate way to deal with an offence or crime.

This expression refers to the law of retribution as set out in the Old Testament (Exodus 21:24), known as lex talionis .