以其人之道还治其身

dose sb. with his own physic, pay sb. back in his own coin, serve sb. with the same sauce

yǐ qí rén zhī dào hái zhì qí shēn ㄧˇ ㄑㄧˊ ㄖㄣˊ ㄓ ㄉㄠˋ ㄏㄞˊ ㄓˋ ㄑㄧˊ ㄕㄣ