One of the mysteries in the Torah is how many years the Jewish people spent in Mitzrayim. When
Hashem first informs Avraham of the galus in Parshas Lech Lecha, He describes how B’nei Yisrael will
be slaves for four hundred years - “yado’a tayda ki ger yihyeh zaracha b’eretz lo lahem v’avadum v’inu
osam arba me’os shanah” (Bereishis 15:13). However, later, in Parshas Bo, when recounting how many
years the Jewish people spent in Mitzrayim, the pasuk states that they were there for four hundred and
thirty years - “umoshav B’nei Yisrael asher yash’vu b’Mitzrayim sheloshim shanah v’arba me’os shanah”
(Shemos 12:40). To complicate matters further, Chazal teach that B’nei Yisrael were not in Mitzrayim for
either of these amounts of time, rather they were there for only two hundred and ten years. (See Rashi,
Bereishis 42:2.) How are these various sources to be reconciled?
Rashi (Bereishis ibid and Shemos ibid) explains that each of the aforementioned counts started at
a different time. B’nei Yisrael’s sojourn in Mitzrayim was indeed two hundred and ten years, as Chazal
relate. The period of four hundred years, on the other hand, is not a description of their time in Mitzrayim,
but of the time that Avraham’s children would be “strangers in a foreign land.” This includes not only
Mitzrayim, but all the lands in which Avraham’s children lived as strangers. From the time Yitzchak was
born, Yitzchak lived in a land which was not his own, and so the count of four hundred years began with
his birth. As for the four hundred and thirty years in Parshas Bo, Rashi explains that this count began from
the time of the b’ris bein hab’sarim in which Avraham was informed of the galus. This event took place
thirty years before Yitzchak was born, and therefore transpired four hundred and thirty years before B’nei
Yisrael left Mitzrayim. According to this, the pasuk in Parshas Bo is to be read as describing not only the
sojourn in Mitzrayim, but that of Mitzrayim and all other lands in which Avraham’s children were
strangers.
Ramban (Shemos ibid) notices a fundamental difficulty with Rashi’s explanation. Yitzchak was
born when Avraham was one hundred years old. Consequently, thirty years prior, when, according to the
above calculation, the b’ris bein hab’sarim took place, Avraham was seventy years old. This is
problematic because the b’ris bein hab’sarim occurred in the land of Israel, yet Avraham did not arrive
there until age seventy five. (See Bereishis 12:4. See also Tosafos Berachos 7b s.v. Lo, Rosh Yevamos
6:12, and Da’as Zekeinim Bereishis 12:4 for resolutions of Rashi.)
Due to his question, Ramban offers a different interpretation. In his view, the four hundred years
which were conveyed to Avraham represent Hashem’s original plan. These years were to begin with the
b’ris bein hab’sarim and conclude after the two hundred and ten years that B’nei Yisrael resided in
Mitzrayim. (See how Ramban there explains the pasuk’s implication that the count only relates to
Avraham’s children, and not to himself.) However, this plan would only be followed if, at the culmination
of the four hundred years, B’nei Yisrael were worthy of redemption. If not, the exile would continue until
they became worthy. Ramban explains that, at the conclusion of the four hundred years, the Jewish people
were indeed not worthy of redemption. They had become idolaters and sinners in Mitzrayim and, as such,
the exile continued.

Ramban writes that this understanding may account for Chazal’s teaching (Sanhedrin 92b) that
the children of Ephraim left Mitzrayim thirty years early. Their escape was not a mere act of desperation,
rather they counted until the end of the four hundred year prophecy and, when its conclusion arrived, they
thought it was time to leave. They did not realize that the prophecy would only be fulfilled if the Jewish
people were worthy, which they were not.
Given this analysis, Ramban wonders what changed after the next thirty years? Were the Jewish
people any less idolatrous and any less sinful after four hundred and thirty years than after four hundred?
Ramban assumes that they were not, and that, indeed, the galus should have lasted even longer. The only
reason it did not was because B’nei Yisrael began to daven - “vayhi vayamim harabim haheim vayamas
Melech Mitzrayim vayayanchu V’nei Yisrael min ha’avodah vayizaku vata’al shavasam el HaElokim min
ha’avodah” (Shemos 2:23). They were still engrossed in the same sins that they had been thirty years
earlier, but because they davened their fate was altered.
This understanding of the redemption from Mitzrayim carries profound implications as to
tefillah’s capacity. Had they not davened, Bnei Yisrael would not have been redeemed from Mitzrayim.
They were a people steeped in sin and distant from the standards Hashem held for them; but because they
davened, Hashem’s decree was changed. Tefillah alone was able to afford them a merit of which they
were otherwise undeserving.
Chazal describe tefillah as one of the things which “stands at the height of the world.” (See Rashi,
Berachos 6b s.v. devarim.) This reality featured prominently in the very first Jewish national redemption,
and its message is instructive as to how we are meant to approach, cherish, and capitalize upon our
opportunities to daven to Hashem.