Tanach · Rishonim on Tanach · Ramban · Torah
Ramban on Deuteronomy 9:5/רמב"ן על דברים ט׳:ה׳
אוְטַעַם וּלְמַעַן הָקִים אֶת הַדָּבָר, שֶׁאָמַר וַעֲבָדוּם וְעִנּוּ אֹתָם אַרְבַּע מֵאוֹת שָׁנָה וְדוֹר רְבִיעִי יָשׁוּבוּ הֵנָּה (בראשית טו טז):
1AND THAT HE MAY ESTABLISH THE WORD WHICH THE ETERNAL SWORE UNTO THY FATHERS. The purport thereof124 is that He had said and they shall serve them; and they shall afflict them four hundred years.125 And in the fourth generation they shall come back hither.126, Verse 16. Therefore it could not be postponed to a later generation.