Allah’s Quran 42:40]
[Principle #1:] An evil act should be retaliated by an equal act [eye for an eye]; however,
[principle #2:] God rewards those who pardon and lead a righteous life.
[Principle #3:] God does not love the wrongdoers [who retaliate excessively].

Prophet (peace be upon him) has said:
[Malik’s Muwatta, Book #43, Hadith #43.21.15a] “Retaliation is between women as it is between men. That is because Allah, the Blessed, the Exalted, said in His Book, ‘We have written for them in it that it is a life for a life and an eye for an eye, a nose for a nose, and an ear for an ear, and a tooth for a tooth, and for wounds there is retaliation.‘ (Sura 5 ayat 48) Allah, the Blessed, the Exalted, mentioned that it is a life for a life. It is the life of a free woman for the life of a free man, and her injury for his injury.” Malik said about a man who held a man fast for another man to hit, and he died on the spot, “If he held him and he thought that he meant to kill him, the two of them are both killed for him. If he held him and he thought that he meant to beat him as people sometimes do, and he did not think that he meant to kill him, the murderer is slain and the one who held him is punished with very severe punishment and jailed for a year. There is no killing against him.”