Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 307
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 307, with English translation by Maimonides (Rambam).
שלא לגלח שיער הנתק, שנאמר "ואת הנתק, לא יגלח" (ויקרא יג,לג).
Not to shave the hair around a bald spot brought about by tzara’at], as [Leviticus 13:33] states: "And he shall not shave the bald spot."