Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 225
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 225, with English translation by Maimonides (Rambam).
שלא לקצור ספיחי יובל כשאר השנים, שנאמר בו "לא תקצרו את ספיחיה" (ויקרא כה,יא).
Not to reap crops that grow on their own in the Jubilee year in the same manner as in an ordinary year, as [Leviticus, ibid.] states: "Do not harvest the crops which grow on their own."