This reading is from the special Torah portion read on the Shabbat during the festival of Sukkot. The complete reading for the intermediate Shabbat is Exodus 33:12-34:26.
He said: I hereby make a covenant. Before all your people I will work such wonders as have not been wrought on all the earth or in any nation; and all the people who are with you shall see how awesome are the Lord's deeds which I will perform for you. Mark well what I command you this day. I will drive out before you the Amorites, the Canaanites, the Hittites, the Perizzites, the Hivites, and the Jebusites.
Beware of making a covenant with the inhabitants of the land against which you are advancing, lest they be a snare in your midst. No, you must tear down their altars, smash their pillars, and cut down their sacred posts; for you must not worship any other god, because the Lord, whose name is Impassioned, is an impassioned God. You must not make a covenant with the inhabitants of the land, for they will lust after their gods and sacrifice to their gods and invite you, and you will eat of their sacrifices. And when you take wives from among their daughters for your sons, their daughters will lust after their gods and will cause your sons to lust after their gods.