출애굽기 12:41의 주석

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.