Rashi on Deuteronomy 29:15/רש"י על דברים כ״ט:ט״ו

1כי אתם ידעתם וגו׳ FOR YE KNOW [HOW WE HAVE ABODE IN THE LAND OF EGYPT] etc. — The meaning of these verses is: Because you have seen the conduct of the other nations, and perhaps the heart of one of you might beguile him to follow them, — as it goes on to state, “Lest there should be among you a man, or a woman … [whose heart turneth away this day from the Lord]”, — on this account I must place you under an oath.