Rashi on Deuteronomy 19:21/רש"י על דברים י״ט:כ״א

1עין בעין EYE FOR EYE — i.e. monetary compensation; similarly also “tooth for tooth” etc. (Sifrei Devarim 190:16; Bava Kamma 84a; cf. also Rashi on Exodus 21:24).