The problem with Rabbah’s explanation above is that it doesn’t explain why one still takes the lulav if the first day falls on Shabbat.
At first, this is easily answered. The end of the mishnah itself says that the rabbis decreed that if the first day falls on Shabbat, one should take the lulav in one’s own home. Not in the synagogue.
The Talmud now has an additional problem—what about before they made this decree. As we recall, the mishnah describes people bringing their lulavim to synagogue before Shabbat so they wouldn’t have to carry them. But why allow this at all—why didn’t we fear that they would forget to bring them the day before and then they would end up carrying on Shabbat.
The answer is that since taking the lulav on the first day of Sukkot is a mitzvah from the Torah, the rabbis did not decree that one should not do so. The mitzvah from the Torah overrides the fear that one will carry on Shabbat.
The question that the Talmud asks is very illustrative, for it shows that in Babylonia Jews did not take the lulav on the first day of Sukkot even when it fell on Shabbat. In other words, even though the mitzvah is from the Torah on the first day, they still do not take the lulav.
The answer is that in Babylonia they did not know exactly when Sukkot fell because they didn’t know when the New Moon (first of the month, Rosh Hodesh) was determined. I’m not going to get into this too deeply, but in Israel every month they would determine when Rosh Hodesh fell; whether the previous month had 29 days or 30 days. There was no set calendar as we have today (and from the fourth century). This would have consequences for the date of Sukkot and Pesah (and the other holidays as well). But in Babylonia or elsewhere outside of Israel, they wouldn’t find out when Rosh Hodesh was until much later. That is how the custom to keep two days of Yom Tov in the Diaspora was formed. Since they weren’t really sure if the day was the first day of Sukkot or not, they did not take the lulav.
The Talmud asks somewhat rhetorically—why doesn’t the lulav override Shabbat in Israel where they do know when the New Moon is declared? The answer is that it does. This is proven by comparing two mishnayot. In one mishnah the people are described as bringing their lulavim to the Temple and in another mishnah they bring their lulavim to the synagogue. The first mishnah refers to a time when the Temple still stood and the second mishnah to the period following its destruction, proving that Jews in Israel continue to take the lulav even in the absence of the Temple.
I should note that currently in Israel, the same rules as the Diaspora apply. No one takes the lulav on Shabbat, even if it falls on the first day.
This section opens with a discussion of how we know that one has to take the lulav on the first day of Sukkot even in the “provinces.” This term refers either to land outside of Jerusalem, or to any place outside of the Temple, including the rest of Jerusalem.
The baraita cited here deals with the first four words of Leviticus 23:40 which refers to the lulav. Taken all together this baraita teaches that everyone must take a lulav, it must belong to them, they should do so on Shabbat, anywhere, even in the Provinces, but only on the first day of Sukkot. On other days, at least in the Provinces, one does not take a lulav on Shabbat.
The Talmud now raises the difficulty that we shouldn’t even need a verse to allow taking the lulav on Shabbat. What could possibly be problematic with just lifting up the lulav?
Rava answers that the verse allows one to do things on Shabbat that would enable one to take the lulav. This would include even cutting the lulav down from the tree which would normally be a Shabbat prohibition. But this is only according to R. Eliezer. The other sages would not agree, as we shall see below.
R. Eliezer reads the verse as if it emphasizes that one can do anything necessary to get a lulav even on Shabbat.
The Talmud now asks, as it often does, what does the other side in a debate do with the words that the rival used as a basis for his halakhah. R. Eliezer used the word “on the day” to prove that one can do anything necessary to get a lulav on Shabbat. The rabbis disagree. So what do they do with that word?
They use it to rule that the lulav must be taken during the day and not at night.
The Talmud continues in its usual manner. R. Eliezer has used the word “on the day” to teach that one can do anything to prepare a lulav on Shabbat. So how does he learn that one takes the lulav during the day and not at night.
He learns it from the word “days” at the end of the verse.
The rabbis don’t learn from the verse used by R. Eliezer because we might have thought that the word “days” refers to days and nights, as it does for the Sukkah. Jews are obligated to dwell in the Sukkah not just during the day, but also at night. But this is not true for the lulav, which is taken only during the day. To avoid this faulty learning, the rabbis derive the rule for the lulav from the word “on the day.”
This section contains a long baraita that teaches that one dwells in the Sukkah during both days and nights.
The Torah states that one must dwell in the Sukkah for seven days. The question is how we know that “days” means nights as well? After all, when it came to the lulav, we interpreted the word “days” to mean just during the daytime. One does not take the lulav at night. So, if we were to compare the rule of the sukkah to the rule of the lulav, we would not have to dwell in the sukkah at night.
But there is another context in which someone is told to do something for seven days. In Leviticus chapter eight, Moses and Aaron prepare for the initial consecration of the priesthood and the Tabernacle. At the end of the chapter, Moses is told to dwell at the opening of the Tent of Meeting for seven days. This “seven days” means days and nights. So too when it comes to Sukkot, the word “days” can mean days and nights.
Since the mitzvah of Sukkah could be like lulav and observed only during the day or like the preparations for the consecration of the Tabernacle and observed day and night, we must decide to which it is more similar. But this is also problematic. On the one hand it is similar to the “preparations” for inherently it is a mitzvah meant to be performed for an extended period of time. The lulav, in contrast, is a mitzvah that can be fulfilled in a single moment. So it would seem that it would be most proper to compare the sukkah with the “preparations,” in which case “days” means nights as well.
But lulav is a mitzvah meant for future generations—it is not just a onetime event like the “preparations.” Since the sukkah is also obviously a mitzvah for the generations, it would seem that we should compare it with the lulav and not the “preparations.”
Thus this analysis in the end fails. We can’t use this type of comparison to understand why we believe that “days” with regard to the sukkah means days and nights.