INTRODUCTION: The Halakhot of K'riat Sh'ma, comprising one Mitzvat
Aseh, namely to read K'riat Sh'ma twice a day. The explanation
of this Mitzva is in these chapters:
Q1: Why does Rambam reckon K'riat Sh'ma as only one Mitzva,
even though there are two distinct times for it?
YF (Yitzchok Fishman ): It is only
one Mitzva because both times are derived from the same place.
YE (Yitz Etshalom): According to that
reasoning, Rambam should reckon hand-Tefillin and head-Tefillin
as one Mitzva (he doesn't) - since they are derived from the same
The question becomes stronger when we note that several Rishonim
(Sa'adia, Ramban) reckoned K'riat Sh'ma as two separate Mitzvot.
Ramban's argument is as follows: Since it is possible to fulfill
one (e.g. evening Sh'ma) without fulfilling the other (morning
Sh'ma), the two are separate Mitzvot. Rambam himself uses this
argument to explain why the four species taken during Sukkot are
one Mitzva: Since all four are necessary components in the
fulfillment of the Mitzva, it should be considered one Mitzva
(Sefer HaMitzvot, Shoresh 11). Following that reasoning, Rambam
should reckon K'riat Sh'ma as two separate Mitzvot.
In the Introductory Shiur, we discussed various possible
"Kiyyumim" (Mitzvot which are fulfilled) in K'riat Sh'ma - Talmud
Torah (Tosafot, RAAVAN), "Yichud Hashem" - declaring God's unity
(Sa'adia), "Kabbalat 'Ol Malkhut Shamayim" - acceptance of God's
authority (Yere'im). We don't yet know which of these, if any,
are considered by Rambam to be woven into the fabric of K'riat
Talmud Torah: It is possible to understand K'riat Sh'ma as the
two daily "flash points" of ongoing Talmud Torah. This notion may
be found in the Gemara in Menahot (99b): This Gemara follows a
discussion of R. Yose's opinion regarding the consistent presence
of "Lechem haPanim" - showbread - in the Kodesh. The Torah
commands us to have the Lechem haPanim "in front of Me *Tamid*".
The first opinion details how two Kohanim would stand and remove
the old Lechem haPanim on Shabbat and, as two others would be
sliding the new Lechem on the Table, they would slide it off -
that the Lechem should be there "Tamid". R. Yose argued that
even if the old Lechem was removed on Shabbat morning and the new
one was placed at the end of Shabbat, it was still considered
"Tamid" - consistently present. Based on this reasoning, the
Gemara contends that a person could be considered to be learning
constantly - i.e. "day and night" - with minimal study by day and
"R. Yohanan said in the name of R. Shim'on b. Yohai: Even if a
person only reads Keri'at Sh'ma in the morning and the evening,
he has fulfilled 'This book of the Torah shall not depart out of
If K'riat Sh'ma is the daily/nightly anchor of Talmud Torah, it
may certainly be considered one Mitzva - for we don't reckon
daytime learning and nighttime learning separately, as they are
Yichud Hashem/Kabbalat Ol: There is room to argue that Rambam
considers K'riat Sh'ma as a Kiyyum of Yichud Hashem. In Sefer
haMitzvot, Mitzvat Aseh #2, he uses the verse of Shma Yisra'el as
the source for the Mitzva of declaring God's Unity - and he
refers to this declaration as "Acceptance of the Authority of
God". Since Yichud Hashem is a Mitzva which is not bound by
time, and K'riat Sh'ma is the twice-daily declaration of this
constant awareness/Mitzva, it stands to reason that it is one
Mitzva: Declaring God's unity twice a day.
Rambam may provide an answer for us; in Sefer haMitzvot, Shoresh
11, he explains that even though the blue and white threads of
Tzitzit may be independently worn (the absence of one does not
invalidate the other) - "Tzitzit" is still considered one Mitzva
"...when it is one matter, for the aim of Tzitzit is 'In order
that you remember [the Mitzvot]', therefore, the whole matter
which creates the commemoration is counted as one..."
In the same way, since the purpose of both daytime and nighttime
K'riat Sh'ma is, in any case, one goal (whatever the aim - study,
declaring God's Unity - it is the same goal during the day and at
night) - we may consider it one Mitzva.
Q2: Why does he term it "twice a day", as opposed to "at night
and during the day"?
YE: Following the answer above, the essential Mitzva is not
rooted in its specific times, rather in the "twice a day" - two
points during the 24-hour period to fulfill this Mitzva and all
that follows from that.