Commento su Esodo 12:41

ויהי מקץ שלשים שנה וגו' ויהי בעצם היום הזה AND IT CAME TO PASS AT THE END OF THE 430 YEARS … EVEN ON THE SELF-SAME DAY — The addition of the latter phrase tells us that as soon as the predetermined end of the bondage arrived the Omnipresent did not detain them even as long as the twinkling of an eye (Mekhilta d'Rabbi Yishmael 12:42). For on the fifteenth of Nisan the ministering angels had come to Abraham to announce to him the promised birth of Isaac, and on the fifteenth of Nisan Isaac was born, and on the fifteenth of Nisan the decree “between the parts” relating to Israel’s slavery was made.

ויהי מקץ שלושים שנה, It was at the end of 430 yers, etc." The Torah does not tell us what happened at that time, otherwise why would the word ויהי be repeated immediately afterwards. If the Torah had alluded to the time of the Exodus the second ויהי would be superfluous. Another thing requiring exegesis is what painful element is alluded to in the word ויהי in this instance.

ומושב בני ישראל אשר ישבו במצרים (עד סוף) שלושים שנה וארבע מאות שנה, after the birth of Yitzchok. At any rate, out of these 400 years the Israelites resided in Egypt for only 210 years at the tail end of the 430 years mentioned at the beginning.

V. 41. כל צבאות ד׳, wie schon wiederholt bemerkt, ward Israel als eine Vielheit von charakteristisch verschiedenen Volksstämmen begriffen, die alle in ihrer gesonderten Eigentümlichkeit sich um den einen Herrn und Führer scharten.

Perhaps the painful element referred to is the very length of time it took for the people to be redeemed. Had they possessed the necessary merit they would not have had to wait until the pre-arranged timetable, i.e. מקץ, the end of the time originally allocated for their bondage. Alternatively, the pain alluded to is the very length of the 430 years mentioned earlier as the time the people sojourned in Egypt.

ויהי בעצם, it was on that same day, etc. The Torah may use the expression to tell us that though the Israelites departed on that day, the troubles of the Egyptians had not come to an end. We have a reference to the Egyptians being busy on that day burying their dead (Numbers 33,4) whereas at the same time the Israelites left Egypt their heads held high.