Selected Halachos Related to Parshas Parshas Tzav - Shabbos Hagadol
By Rabbi Doniel Neustadt
The following is a discussion of Halachic topics related to the Parsha of the week.
For final rulings, consult your Rav.
MATZAH - HOW MUCH NEED WE EAT?
QUESTION: How much Matzah must one eat on Seder night?
DISCUSSION: There is a Biblical commandment to eat matzah on the
first night(1) of Pesach. The Talmud explains that "eat", by
definition, means to eat at least an amount equivalent to the
size of an olive, a k'zayis. Men and women equally are obligated
to perform this mitzvah. Boys and girls, too, once they are old
enough to understand what the Seder is all about, should be
taught to eat a portion of matzah lishmah, "for the sake of the
mitzvah", as the Torah requires.
In the opinion of many authorities, the proper, l'chatchillah
manner of eating the k'zayis of matzah is to chew the matzah
thoroughly and swallow it entirely in one swallow(2). If it is
difficult to do so(3), however, one may take up to three(4)
minutes(5) to eat the kzayis. [An elderly person who is only
able to chew slowly, children under the age of bar/bat
mitzvah(6), or anyone with a medical condition, can rely on the
lenient views which allow for a time-span of up to nine minutes.]
It follows, therefore, that anyone who eats one k'zayis of
matzah within the prescribed time satisfies his basic
obligation. But while the basic mitzvah is easy to understand
and fulfill, there is much DISCUSSION among the poskim
concerning several technical details of how best to perform this
important mitzvah: Some of the issues debated are:
Should the k'zayis of matzah be broken off from the upper, whole
matzah, or from the middle, broken matzah?
Can two blessings - ha-motzi and al achilas matzah - be recited
over one matzah(7), or must we recite one blessing over one
matzah and the other blessing over the other?
If, indeed, the two blessings must be recited over two separate
matzos, which blessing is said over which matzah?
In response to these and other concerns and in order to fulfill
the mitzvah in the most l'chatchillah manner(8), Shulchan Aruch
advises that one eat two k'zayis portions, one from each matzah.
But since we are unsure which is the "real" k'zayis, nor are we
sure which blessing corresponds to which matzah, we recite both
blessings over both pieces of matzah (the top and the middle
one(9)), break them off together(10), and eat a k'zayis from
each one of them together(11). ["Together" means inserting both
k'zayis portions into one's mouth and chewing them, and then
swallowing one k'zayis at a time, if possible. If it is
difficult to insert both k'zayis portions into the mouth at one
time, one can take up to three minutes to swallow both
portions(12).] Thus one is actually eating two kzayisim.
But it is essential to understand that eating a second k'zayis
is not nearly as important as eating a first one. Clearly and
unequivocally, one fulfills his basic obligation by eating any
k'zayis of any matzah, regardless of which matzah or combination
of matzos it is taken from. Bearing this in mind, the following
points need to be clarified:
There are poskim who QUESTION this entire stringency(13) and
require only one k'zayis to be eaten(14).
Even among the poskim who recommend that two portions be eaten,
there are several who hold that only the person conducting the
Seder [or anyone breaking the matzos and reciting the blessings
over them] must eat two portions. The other participants need to
eat only one portion(15).
While many poskim seem to hold that everyone should eat two
k'zaiysim(16), it is, according to all views, a stringency and a
hiddur mitzvah, not a basic halachic obligation. Thus elderly or
weak people, people who can only stomach a small amount of
matzah, small children, and anyone else who finds eating matzah
difficult, need not force themselves to eat more than one
k'zayis of matzah. [The k'zayis should be a combination of the
top and middle matzos.]
One who is able to eat two portions, but cannot eat them
together or even within three minutes, should eat them
separately, each one within three minutes. He should first eat
the k'zayis which comes from the upper, whole matzah, and then
the kzayis which is taken from the middle matzah(17).
HOW MUCH IS A K'ZAYIS?
The amount of a k'zayis as it pertains to matzah has been
extensively debated among the classic poskim and contemporary
authorities. We will list briefly the points debated:
Is a k'zayis the equivalent of half an egg, like the Rosh
writes, or a third of an egg, like the view of the Rambam?
Are the eggs today the same size they were during the days of
the Talmud or are they smaller, as some evidence seems to
Is the k'zayis measured by weight or by volume? (In other words,
do we include air holes when measuring the k'zayis or not?)
When measuring an egg, what size egg is used? Is the shell
included when measuring the egg?
There are no clear-cut, definitive answers to these questions.
While several poskim allow for the lesser amount, the view of
the Mishnah Berurah is that when it comes to matters of Biblical
law, such as the mitzvah of eating matzah, we ought to be
stringent, following the principle of safek deorayisa
lchumrah(18). Thus it is proper to follow the more stringent
measurements for the k'zayis. [Sick and elderly people may rely
on the lenient size of a k'zayis, which is about half of the
But as explained earlier, the Biblical obligation is to eat
only one k'zayis. That one k'zayis should be reckoned according
to the maximum standard, as it is a Biblical requirement. But
the second k'zayis, the one that is eaten to satisfy the concern
of the poskim regarding the technical details of the mitzvah, is
not Biblically mandated. For that second k'zayis we can surely
rely upon the smaller, more lenient size. Indeed, some
poskim(19) maintain that one need eat only one large k'zayis to
meet all requirements: The Biblical obligation will be met with
the large k'zayis; the technical details obligation will also be
satisfied with the one large k'zayis, since a large k'zayis can
contain two small portions of k'zayis.
There are several methods for estimating the size of one large
k'zayis: About 2/3 of a standard machine matzah; about 24 grams
(0.8 oz.) of hand matzah(20); about the space of a
loosely-extended palm (including the thumb) of an average
Note: Matzah that remains on the gums is counted towards the
k'zayis, but whatever gets stuck between the teeth does not.
Burned matzah, or matzah that is not actually ingested because
it has fallen out of one's mouth while eating, do not count
towards the k'zayis either.
The above discussion applies to the matzah eaten at the end of
the meal, the afikoman, as well. There, too, one k'zayis is
required(22) while the second k'zayis is only recommended(23)
and anyone who finds it difficult to eat two portions should eat
only one(24). By eating one large k'zayis, one will surely meet
all of his requirements.
1. Outside of Eretz Yisroel, there is a Rabbinic obligation on
the second night as well.
2. Mishnah Berurah 475:9 and 41, based on Magen Avraham and
Shulchan Aruch Harav. But other poskim rule that this is not
required; see Eliyahu Rabbah 475:2 and 12; Aruch ha-Shulchan 4,
Dinim v'Hanhagos 17:34 quoting he custom of the Chazon Ish;
Yechaveh Da'as 1:17.
3. Most people find this difficult to do - Moadim u'Zmanim 3:259,
especially if they use a large piece for a k'zayis.
4. Igros Moshe O.C. 4:41. Some poskim allow only two minutes
while others allow up to four minutes. [If, mistakenly, one took
longer than four minutes to eat his portion, he should eat
another k'zayis, but without reciting the blessings.]
5. The time begins from the beginning of the swallowing, not from
the beginning of the chewing; Kol Dodi 14:7.
6. Harav S.Z. Auerbach (Shemiras Shabbos K'hilchasah 54, note
7. Based on the rule of aiyn osin mitzvos chavilos chavilos.
8. As the Chasam Sofer writes: This mitzvah (eating matzah on
Pesach) is the only Biblical mitzvah of "eating" that has
remained for us to fulfill in these times when the bais
ha-mikdash is not standing... it is proper to fulfill it in a
manner which satisfies all opinions l'chatchillah... (Teshuvos,
9. When the first blessing - ha-motzi - is recited, all three
matzos should be held so that lechem mishneh can be fulfilled.
10. Mishnah Berurah 475:3. Other poskim do not insist that they
be broken together; see Shulchan Aruch ha-rav 475:5.
11. The two portions cannot be eaten separately, since we are
unsure which is the "correct" one. Eating one before the other
could create questions of hefsek between the "correct" blessing
and the "correct" k'zayis.
12. See Orchos Rabbeinu 2:66 that this was the custom of the
Chazon Ish and Harav Y.Y. Kanievsky. This is also the common
13. See Beiur Halachah who questions the basis for this practice
and its authenticity.
14. Chazon Ish is quoted by several sources as ruling that there
is no need to eat more than one k'zayis, and this was the custom
of the Chazon Ish himself; see Orchos Rabbeinu 2:70.
15. Harav S.Y. Elyashiv (quoted in Seder ha-Haruch 79:4); Hagadas
Moadim u'Zmanim, pg. 97; Kol Dodi 14:3. See also Shemiras
Shabbos K'hilchasah 55 note 15 quoting Harav S.Z. Auerbach.
[Igros Moshe O.C. 5:16 recommends that each male household
member have in front of him three matzos, so that each one
should have enough matzah for two portions of k'zayis.]
16. Kitzur Shulchan Aruch 119:5; Minhagei Chasam Sofer 10:17.
17. O.C. 475:1 and Mishnah Berurah 10. He should recline when
eating both portions.
18. Mishnah Berurah 486:1.
19. Seder Pesach K'hilchaso 8:4, quoting Harav S.Y. Elyashiv and
Harav N. Karelitz.
20. It is difficult to estimate the size of a k'zayis of a hand
matzah, since the matzos vary in size and in thickness.
Generally, a little more than a quarter of an average matzah is
a large k'zayis; Piskei Teshuvos 486:1.
21. Halaylah ha-Zaeh, pg. 19. Chazon Ish and Harav Y.Y. Kanivesky
measured the large k'zayis as the space of their
loosley-extended palm without the thumb; Orchos Rabbeinu 2:66.
22. According to most opinions, the obligation is Rabbinical in
23. Mishnah Berurah 477:1
24. Shulchan Aruch Harav 477:3. Some poskim maintain that women
and children are only obligated to eat one k'zayis for afikoman;
see Seder ha-Haruch 97:8.
Weekly-Halacha, Copyright © 5759 by Rabbi Neustadt, Dr. Jeffrey Gross and
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Rabbi Neustadt is the principal of Yavne
Teachers' College in Cleveland, Ohio. He is also the Magid Shiur of a daily
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