Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 220
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 220, with English translation by Maimonides (Rambam).
לדון במפתה בחמישים שקל עם שאר דינין, שנאמר: "כי יפתה איש" (שמות כב,טו).
To carry out the judgment concerning a seducer, fining him fifty shekels and carrying out the other laws regarding this matter, as [Exodus 22:15] states: "If a person will seduce...."