Sukkah 9B

מתני׳ העושה סוכתו תחת האילן ⁠— כאילו עשאה בתוך הבית. סוכה על גבי סוכה ⁠— העליונה כשרה והתחתונה פסולה. רבי יהודה אומר: אם אין דיורין בעליונה ⁠— התחתונה כשרה.

Mishnah: With regard to one who establishes his sukka beneath a tree, it is as though he established it inside the house and it is unfit. If one established a sukka atop another sukka, the upper sukka is fit and the lower sukka is unfit. R' Yehuda says: If there are no residents in the upper sukka, the lower sukka is fit.

גמ׳ אמר רבא: לא שנו אלא באילן שצלתו מרובה מחמתו, אבל חמתו מרובה מצלתו ⁠— כשרה.

Talmud: Rava said: They taught this halakha that a sukka beneath a tree is unfit only with regard to a tree whose shade is greater than its sunlight, as the source of the shade in the sukka is the tree and not the roofing. However, if its sunlight is greater than its shade, the sukka is fit, as in that case the roofing provides the shade.

ממאי ⁠— מדקתני: ״כאילו עשאה בתוך הבית״: למה לי למיתני ״כאילו עשאה בתוך הבית״? ליתני ״פסולה״! אלא, הא קא משמע לן דאילן דומיא דבית: מה בית צלתו מרובה מחמתו ⁠— אף אילן צלתו מרובה מחמתו.

The Talmud asks: From where does Rava reach this conclusion? The Talmud answers: He learns this from the fact that the Mishnah teaches: It is as though he established it inside the house. Why do I need the Mishnah to teach: It is as though he established it inside the house? Let the Mishnah teach simply: It is unfit. Rather, this is teaching us that in the context of this halakha, a tree is similar to a house; just as with regard to a house, its shade is greater than its sunlight, so too, with regard to a tree, it invalidates the sukka only if its shade is greater than its sunlight.

וכי חמתו מרובה מצלתו, מאי הוי? הא קא מצטרף סכך פסול בהדי סכך כשר! אמר רב פפא: בשחבטן.

The Talmud asks: And even if the sunlight is greater than the shade of the tree, what of it? Why does Rava deem the sukka beneath the tree fit in that case? Isn’t there unfit roofing, the uncut branches of the tree, joining together with the fit roofing on the sukka, rendering even the fit roofing on the sukka unfit? Rav Pappa said: This is referring to a case where one lowered the uncut branches and combined them with the fit roofing so that the branches still attached to the tree are inconspicuous. Given that the majority of the roofing is fit, the roofing in its entirety is fit.