eye for an eye, an - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Punishment in which the offender suffers what the victim has suffered, exact retribution, as in Joe believed in an eye for an eye; stealing his client would have to be avenged. This idiom is a quotation from the Bible, which has “Life shall go for life, eye for eye, tooth for tooth” (Deuteronomy 19:21); the idea is contradicted in the New Testament (see turn the other cheek).