Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 31
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 31, with English translation by Maimonides (Rambam).
לשלח טמאים ממחנה שכינה שהוא המקדש, שנאמר: "וִישַׁלְּחוּ מִן הַמַּחֲנֶה כָּל צָרוּעַ וְכָל זָב וְכֹל טָמֵא לָנֶפֶשׁ" (במדבר ה, ב).
To send impure people out from the camp of the Divine Presence - i.e., the sanctuary - as [Numbers 5:2] states: "And you shall send from the camp all the leprous, any zav, and anyone who has contracted impurity because of a corpse."