an eye for an eye以眼還眼
an eye for an eye, noun phrase, 以眼還眼, repayment in kind, as revenge for an offense.
Ex.例：An eye for an eye is never the right way to resolve any conflict.
Perhaps you already know there’s a second half to this phrase, which is – “a tooth for a tooth以牙還牙.” But do you know that the whole expression is actually taken from the Bible?
“You have heard that it was said, 'Eye for eye, and tooth for tooth.' But I tell you, 'Do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also.'”
Jesus is teaching us that to conquer evil, we must not do evil but rather do good. (耶穌教導我們要戰勝邪惡，以行善來取代行惡事。)
The way to show our love for God is by loving and forgiving the people around us, even our enemies(仇敵). This is not to say we willingly and willfully let others hurt us, but rather we choose not to insist on personal rights. (這不表示任意讓仇敵傷害我們，而是我們堅持不以自身權益為先來處理衝突！)
The conduct of loving and forgiving our personal offenders may be a big surprise for those who experience it. How this surprise element truly reflects the amazing grace that is central to the gospel!
By the way, have you noticed there’s a third body-part
idiom (諺語) in the Bible verse above besides ‘eye’ and ‘tooth’? Right! It’s
“turn the other cheek,” (挨揍後不還手，反而轉過另一邊臉來讓人打。)
which shares the similar meaning of choosing to respond to insult or injury by avoiding the measure of an eye for an eye.