Rashi on Deuteronomy 22:18/רש"י על דברים כ״ב:י״ח

1ויסרו אתו [AND THE ELDERS … SHALL TAKE THE MAN] AND CHASTISE HIM — i.e. with lashes (Sifrei Devarim 238:2; Ketubot 46a; cf. Onkelos).