Tafsiran Ulangan 29:15: Rashi, Chizkuni, Da'at Zekenim & Ramban

כי 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.

אשר ישבו בארץ מצרים, “who had dwelled in the land of Egypt;” together with the ones who had still dwelled in the land of Egypt (who had been minors at the time of the Exodus) and who had experienced all that you have witnessed during the last forty years in the desert, etc. The decree to die in the desert had applied only to males who had been twenty years of age at the time of the Exodus, and had not been older than 60 years at the time when it was issued.

כי אתם ידעתם את אשר ישבנו בארץ מצרים, “for you (only) know that we have once lived in the land of Egypt;” this verse proves that there were still survivors of the period of slavery that had come out 40 years ago, and had not died by the decree G–d issued after the sin of the spies. They had either been younger than twenty at the time of the Exodus or had been over 60 years of age already at that time.