ˇㄧㄢˇㄏㄨㄢˊㄧㄢˇyǐyǎn‑huányǎnˇㄧㄚˊㄏㄨㄢˊㄧㄚˊyǐyá‑huányá

以眼还眼,以牙还牙
  1. 比喻採取同樣手段還擊對方 雙方一味以眼還眼,以牙還牙豈不是沒完沒了?」。

an eye for an eye, a tooth for a tooth (idiom)​, fig. to use the enemy's methods against him, to give sb a taste of his own medicine