It seems that it is possible for a day on which one observes Nezirus to
count for two different sets of Nezirus -- for his own Nezirus and for the
Nezirus that he accepted for his son. If this is true, though, then why, in
the second case of the Mishnah, where his son is born after the seventieth
day, do the days of the Nezirus for his son that coincide with the days of
the 100-day Nezirus (for example, day 71 to day 100) not count for both sets
of Nezirus? Why, in that case, do we say that he cannot count those days
towards his own Nezirus, and, after he finishes the Nezirus for his son, he
must make up another 29 days for his own Nezirus? If observing the laws of
Nezirus can count for two sets of Nezirus, then what difference does it make
if the son's Nezirus is entirely included ("Muvla") in the time period of
his own Nezirus or not?

In addition, a Beraisa earlier (14a) says that if a person accepts two sets
of Nezirus -- a 100-day Nezirus as well as a 30-day Nezirus beginning twenty
days from now, he must observe a total of 130 days of Nezirus, even though
the Nezirus that he accepted to observe after twenty days is entirely
included in the Nezirus of 100 days. Why should he not be able to observe
only 100 days to count for both sets of Nezirus?

(a) According to **TOSFOS**, who explains the Mishnah like we described above,
the logic of the Mishnah's ruling might be as follows. A count of days of
Nezirus must reach a completion which will enable the Nazir to bring his
Korbanos. A day can only be counted towards the days of his Nezirus if that
day brings him one day closer to the point at which his Nezirus is completed
(at which he can bring his Korbanos). Therefore, if the Nezirus for the son
is included in his own Nezirus and his own count of 100 days is concluded
after he concludes the Nezirus for his son, then every day of his Nezirus --
including the days he observed for his son as well -- is bringing him closer
to day 100, at which time he can bring the Korbanos for his Nezirus.
However, if his son is born on day 71, then if he counts day 71 towards his
own Nezirus, then day 100 of his own Nezirus will occur before the end of
the Nezirus for his son. Consequently, he will not be able to shave on that
day, since he still needs to conclude the Nezirus for his son. Since he
cannot count day 71 -- the first day of Nezirus for his son -- towards his
own Nezirus, then he cannot count any of the days of the Nezirus for his son
towards his own Nezirus. He must observe two separate periods of Nezirus --
the Nezirus for his son, and then the days for his own Nezirus. After he
concludes his son's Nezirus, he observes another 29 days of his own Nezirus,
after which he is able to shave.
According to this, why is it that if the child is born on day 60, he is able
to observe the days of Nezirus for his son within the days of his own
Nezirus? At the conclusion of the days of Nezirus for his son, it will be
day 90 of his own Nezirus, and he still will not have finished his own
Nezirus and he will not be able to shave for the Nezirus for his son! If so,
all of those days should not count towards the Nezirus for his son! The
answer is that he *is* able to shave on day 90 if he would like to; even
though it is still during the period which he is observing as his own
Nezirus, since he accepted the Nezirus for his son first (that is, he first
accepted upon himself to become a Nazir when his son is born, and then he
accepted upon himself to become a Nazir "from today"), it takes precedence
and he is allowed to shave at the conclusion of that Nezirus, even though it
is during the term that he started observing for his own Nezirus. If he does
shave, however, he will have to wait thirty days from that day in order to
bring Korbanos for his own Nezirus afterwards, because "Ein Taglachas
Pechusim mi'Sheloshim Yom" (he may only bring Korbanos for his Nezirus upon
shaving his hair that has grown for thirty days). Hence, it is not advisable
for him to shave on day 90, and it is better for him to delay shaving until
day 100 when he shaves and brings Korbanos for both his Nezirus and for his
son's Nezirus.

We see that both the days counted for his own Nezirus and for his son's
Nezirus are bringing him closer to a completion and conclusion of the
Nezirus at which point he may bring Korbanos.

Tosfos addresses our second question as well. Why is it that when a person
accepts upon himself Nezirus after 20 days and then he accepts a Nezirus for
100 days, do we not say that he only needs a total of 100 days? Tosfos (13b,
DH O Dilma) explains that when a person does not make his Nezirus contingent
upon an unpredictable event, but rather he says, "I will be a Nazir after 20
days, and I will be a Nazir right away for 100 days," he knows that the
30-day Nezirus that he accepted first will be completed within the 100 days.
If he wanted to be a Nazir for only 100 days, then why did he mention the
Nezirus after 20 days in the first place, if it is included in the 100 days?
It must be that he meant that he will be a Nazir for 30 days, and -- besides
those 30 days of Nezirus which start after 20 days -- he will be a Nazir for
another 100 days, for a total of 130 days. In contrast, when he makes the
Nezirus contingent upon the birth of his son, he does not know whether that
will occur during the 100 days or afterwards, and therefore we may assume
that he intends for the Nezirus to be included in his 100-day Nezirus if the
birth happens to occur before the end of the 100 days. If it occurs
afterwards, then it will be a separate Nezirus of 30 days.

(b) The **ROSH**, cited by the **SHITAH MEKUBETZES**, points out that according to
this explanation the words of the Mishnah, "she'Ein Taglachas Pechusim
mi'Sheloshim Yom," are irrelevant and have nothing to do with the Halachah
in the Mishnah! Why does the Mishnah have to mention how long the Nazir's
hair must grow, if the Mishnah is discussing a case where the Nazir did
*not* cut his hair? The Mishnah is not discussing a case where he cut his
hair and he needs to observe days of "Gidul Se'ar;" the Mishnah is
discussing a case where the child was born before or after seventy days!

Tosfos (13b, DH l'Achar Shiv'im) addresses this question and offers a rather
forced answer, saying that the Mishnah is simply suggesting that it is not
worthwhile to shave after the Nezirus for his son if the Nezirus for his son
is "Muvla" within his own Nezirus, since if he shaves after Nezirus for his
son, he will have to wait extra days of "Gidul Se'ar."

The **ROSH**, though, explains the Mishnah in an entirely different manner
because of this question. He does not have the Girsa in the Seifa that
Tosfos has, that if the child is born after seventy days, it is "Soser."
Rather, he has the Girsa that if the child is born after seventy days, it is
"Soser *Ad Shiv'im*" -- it cancels the amount of days, from his 100-day
Nezirus, between the day on which the child was born and day seventy. For
example, if the child was born on day 80, he loses 10 days because 80 minus
70 is 10. If the child was born on day 90, he loses 20 days.

The Rosh explains that the Mishnah never meant that he counts the Nezirus of
his son at the same time as his own Nezirus. Rather, he always has to
observe 130 days of Nezirus; however, if his child is born before day 70,
then after he finishes counting Nezirus for his son, he must complete 30
more days for his own Nezirus, after which he shaves. However, if his child
is born after day 70, then he has less than 30 days to observe for his own
Nezirus. However, he must shave after he finishes his son's Nezirus before
he is able to complete his own Nezirus. As a result, he will have to add
days to his own Nezirus, because "Ein Taglachas Pechusim mi'Sheloshim Yom."
He will have to observe additional days of "Gidul Se'ar" (29 days of
completion of his Nezirus, plus one day of "Gidul Se'ar"), so that he will
have enough hair-growth in order to shave and bring his Korbanos. If his
child is born on day 71, he loses one day and thus he must add one day for
"Gidul Se'ar." If his child is born on day 80, he must add 10 days of "Gidul
Se'ar," and instead of the 20 days that remained of his 100-day Nezirus, he
has to observe 30 days.

The Rosh, with this explanation, is following his own view elsewhere. The
Rosh earlier (13b) writes that if a person accepts upon himself to be a
Nazir when he has a son, and he also accepts to be a Nazir for 30 days.
After 20 days, he has a child. The Halachah is that he observes 30 days for
the Nezirus for his son and then he shaves, and then he returns to his own
Nezirus and completes the next ten days. However, since he shaved after the
30 days of Nezirus for his son, he needs -- besides observing another ten
days of Nezirus -- another 20 days of "Gidul Se'ar" (see Insights there).

The Hagahah in Tosfos (13b, DH l'Achar) cites the Yerushalmi that says
exactly like the Rosh and says that the Mishnah means that if the child is
born on day 80 of the 100 days, the person loses 10 days; if the child is
born on day 90, he loses 20 days.

In summary, according to the Rosh, a person can never count one day towards
two different sets of Nezirus.

(c) The **HAGAHAH **in Tosfos (13b, DH l'Achar) which cites the Yerushalmi
interprets the Yerushalmi in exactly the opposite way of the Rosh. He
explains that whether the child is born before day 70 or after day 70, the
days of Nezirus for his son *always* count towards his own Nezirus, even
though the Nezirus for his son continues beyond the last day of his own
Nezirus. The Yerushalmi's Girsa in the Mishnah is like that of the Rosh:
when the Mishnah says that if his child is born after day 70, it is "Soser
*Ad Shiv'im*," meaning that if the child is born on day 80 then he loses 10
days, and if he is born on day 90 then he loses 20 days. In what way does he
lose 10 days? He must keep a total of *110* days of Nezirus, rather than 100
days had the child been born before day 70.

In summary, according to the Hagahah, we can always count one day of Nezirus
towards as many sets of Nezirus as we would like.

According to this explanation, how do we explain the Mishnah earlier (13b)
which says that if a person accepts upon himself to observe Nezirus when his
son is born and he accepts a 30-day Nezirus from now, and after 20 days a
child is born, "he stops his own Nezirus and counts Nezirus for his son, and
then completes his own Nezirus?" Why does it say that he stops his own
Nezirus to observe his son's Nezirus, and then he completes his Nezirus
afterwards? The Nezirus for his son should count towards his own Nezirus,
and therefore the 20 days that passed before his son was born plus the first
10 days of the Nezirus for his son should constitute his own Nezirus!

The Hagahah actually asks this question on the Yerushalmi, and because of
this question he offers a forced explanation in the Yerushalmi in order to
have the Yerushalmi agree with the way that Tosfos learns. However, it might
be possible that according to his interpretation of the Yerushalmi, when the
Mishnah says that he "stops" his own Nezirus it simply means that he does
not continue his own Nezirus exclusively and delay the Nezirus for his son
until after his Nezirus is completed, like he must do in the case of the
Reisha of the Mishnah, because by doing so he will have to have a total of
60 days of Nezirus. Rather, "he stops his own Nezirus," meaning that he
starts his son's Nezirus right away, without actually stopping his own, and
he does not have a Nezirus which is exclusively his own, "and afterwards he
completes his own Nezirus," meaning that after day 50, when he has already
completed 30 days of Nezirus for his son, *that* is when he brings the
Korbanos for his Nezirus. It is called being "Mashlim" ("completing" his
Nezirus) since he delayed those Korbanos from day 30 until day 50 due to the
observance of his son's Nezirus.

On this explanation of the Yerushalmi, the question of the Rosh returns.
What does "Ein Taglachas Pechusim mi'Sheloshim Yom" have to do with the
Mishnah? The reason why the Nezirus of his son lengthens the amount of time
that he is observing his Nezirus has nothing to do with shaving after
observing less than 30 days, since he did *not* shave after his son's
Nezirus! We will have to answer similarly to the way that Tosfos answers the
question, by saying that the Mishnah is explaining that if he does not want
to add *more* than 10 days when his son is born on day 80, then he should
not shave at the end of his Nezirus, before the completion of his son's
Nezirus. That is, he should not shave on day 100, but rather on day 110,
because if he shaves on day 100 he will not be able to finish his Nezirus on
day 110, because of "Ein Taglachas Pechusim mi'Sheloshim Yom."