Negative commandment · Lo Ta’aseh #48 of 613
Not to establish a covenant with the seven [Canaanite] nations
שלא לכרות ברית לשבעה עממין
The verse · Devarim 7:2
וּנְתָנָם ה׳ אֱלֹהֶיךָ לְפָנֶיךָ וְהִכִּיתָם הַחֲרֵם תַּחֲרִים אֹתָם לֹא־תִכְרֹת לָהֶם בְּרִית וְלֹא תְחׇנֵּם
“and when the Lord thy God shall deliver them before thee, and thou shalt smite them, then thou shalt devote them to utter destruction; thou shalt make no covenant with them, nor show mercy to them:”
The Rambam’s words
Not to establish a covenant with the seven [Canaanite] nations, as [Deuteronomy 7:2] states: "Do not establish a covenant with them."
שלא לכרות ברית לשבעה עממין, שנאמר "לא תכרות להם ברית" (דברים ז,ב).
Why · Sefer HaChinuch #93
To not make a covenant with the seven nations and likewise with any worshiper of idolatry
“It is from the roots of this commandment to destroy idolatry and all of those who serve it from the world. And these seven nations were the center of idolatry and its first foundation; and because of this, they were uprooted from their Land.”
Who & when
“And there I will write at length about this commandment, with G-d’s help, and tell the reason for why these bad nations are in the world and that this commandment is included in the commandments that are practiced.”
Where in the Mishneh Torah
Hilchot Foreign Worship and Customs of the Nations הלכות עבודה זרה וחוקות הגויים