Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 224
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 224, with English translation by Maimonides (Rambam).
להלקות הרשעים, שנאמר: "והפילו השופט והכהו" (דברים כה,ב).
To whip the wicked, as [Deuteronomy 25:2] states: "The judge will cast him down and beat him."