וּקְח֧וּ אֶת־אֲבִיכֶ֛ם וְאֶת־בָּתֵּיכֶ֖ם וּבֹ֣אוּ אֵלָ֑י וְאֶתְּנָ֣ה לָכֶ֗ם אֶת־טוּב֙ אֶ֣רֶץ מִצְרַ֔יִם וְאִכְל֖וּ אֶת־חֵ֥לֶב הָאָֽרֶץ׃
너희 아비와 너희 가속을 이끌고 내게로 오라 내가 너희에게 애굽 땅 아름다운 것을 주리니 너희가 나라의 기름진 것을 먹으리라
Rashi on Genesis
את טוב אוץ מצרים THE BEST OF THE LAND OF EGYPT — viz., the district of Goshen. He prophesied without knowing what he was prophesying when he said “I shall give you the best of the land of Egypt”, for ultimately they were to make it like the depths of the sea in which there are no fish (i.e. that they would carry away the best of the land when they would leave Egypt) (Berakhot 9b).
Rabbeinu Bahya
ואכלו את חלב הארץ , “and you will eat the fat of the land.” Pharaoh prophesied without being aware that he prophesied. The same applies to verse 20 where Pharaoh said “the best of the whole land of Egypt is yours.” These remarks were allusions to what the Jewish people would do to the Egyptians at the time of the Exodus. We read there (Exodus 12,36) “they emptied out all of Egypt.”
Siftei Chakhamim
It would ... like the depths of the sea which contains no fish. Explanation: There are no fish in the water’s depths; rather, they swim above.