Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 111
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 111, with English translation by Maimonides (Rambam).
להיות המצורע מגלח כל שערו, שנאמר: "וְהָיָה בַּיּוֹם הַשְּׁבִיעִי יְגַלַּח אֶת כָּל שְׂעָרוֹ" (ויקרא יד, ט).
For a person afflicted with tzara’at to shave all of his hair, as [Leviticus 14:9] states: "And it shall be on the seventh day, he shall shave all his hair."