Sukkah 43a and Sukkah 43b, why we do or don’t perform the mitzvah of lulav when the first day of Sukkot is Shabbat, in Israel and out, and the same for aravah, circling the altar either with a willow branch or the lulav bundle. With a side discussion of how we know lulav is only during the day and the mitzvah of sukkah is day and night.
