Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 200
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 200, with English translation by Maimonides (Rambam).
שלא ייראה חמץ, שנאמר "לא ייראה לך חמץ" (שמות יג,ז).
Not to have chametz seen [in one's possession during Pesach], as [Exodus 13:7] states: "No chametz and no leaven may be seen in your territories."