Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 187
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 187, with English translation by Maimonides (Rambam).
לאבד שבעה עממים מארץ ישראל, שנאמר: "החרם תחרימם" (דברים כ,יז).
To destroy the seven nations [that dwelled in] Eretz Yisrael, as [Deuteronomy 20:17] states: "You shall utterly destroy them."