You shall not take revenge…
— Leviticus 19:18
What is taking revenge?
Taking revenge is when you ask someone, "Lend me your sickle," and he says no. The next day he comes to you and asks you "Lend me your hatchet." You respond, "I am not lending to you, just like you did not lend to me."
This is an example of revenge.
—The Talmud, Yoma 23a
It is human nature. When someone wrongs us, we want to retaliate. We are infuriated and hold onto memories of these "wrongs," and when given the opportunity, we respond in kind.
Taking revenge is prohibited in Judaism.
Maimonides writes about revenge in his code of Jewish law:
Taking revenge is an extremely bad trait. A person should be accustomed to rise above his feelings about all worldly matters; for those who understand [the deeper purpose of the world] consider all these matters as vanity and emptiness, which are not worth seeking revenge for."1
Rather, Maimonides continues, if someone who has wronged you comes to ask a favor, you should respond "with a complete heart." As King David says in the Psalms, "Have I repaid those who have done evil to me? Behold, I have rescued those who hated me without cause"(7:5).
In addition, Jewish law forbids us to bear a grudge. Thus, the Talmud explains, you may not even say to the person who wronged you that you will act rightly, even though he or she did not.2
Rabbi Schneur Zalman of Liadi in his code of Jewish law concludes that, "one should erase any feelings of revenge from one's heart and never remind oneself of it."3
The Heart
Not taking revenge is not just about modifying one's actual actions; it is also that the thought of revenge never even enter one's heart.4
The 13th-century Talmudist, Rabbi Aharon HaLevi of Barcelona, explains:
One of the roots of this commandment is that a person should know in his heart that all that happens to him, whether good or bad, is because it is G‑d's will that it happen to him... It was G‑d who wished this to happen, and one should not consider taking revenge from the other person, because the other person is not the reason for what happened.5
(Rabbi Schneur Zalman of Liadi explains in his Tanya that while the person wronged needs to forgive, the person who did the action is still held accountable, for "G‑d has many agents" through whom He can act.6)
The verse prohibiting revenge ends with the famous maxim, "You should love your fellow as yourself." Rabbi Moshe ben Nachman, "Nachmanides," explains that erasing the event from your heart will guarantee that you will never come to transgress the commandment, allowing you to love your fellow, no matter what transpires between the two of you.7
See Is Turning the Other Cheek a Jewish Value? from our Jewish Ethics & Morality section.
By Dovid Zaklikowski 
