Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 190
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 190, with English translation by Maimonides (Rambam).
שלא לאכול קלי מן החדש, שנאמר "וקלי . . . לא תאכלו" (ויקרא כג,יד).
Not to eat roasted grain from newly grown produce before Pesach, as [Leviticus, ibid.] continues: "[Until that day,...] you may not eat... roasted grain..."