Avodah Zarah 48B

מתני׳ לא ישב בצילה, ואם ישב ⁠— טהור, ולא יעבור תחתיה, ואם עבר ⁠— טמא. היתה גוזלת את הרבים ועבר תחתיה ⁠— טהור.

Mishnah: With regard to an ashera, one may not sit in its shade, but if one sat in its shade he remains ritually pure. And one may not pass beneath it, and if one passed beneath it he is ritually impure. If the tree was robbing the public, i.e., if its branches extended over public property, and one passed beneath it, he remains pure.

גמ׳ לא ישב בצילה. פשיטא! אמר רבה בר בר חנה אמר רבי יוחנן: לא נצרכא אלא לצל צילה.

Talmud: The Mishnah teaches: One may not sit in its shade. The Talmud asks: Isn’t this obvious? He is directly benefiting from an object of idol worship. Rabba bar bar Ḥana said that R' Yoḥanan said: It is necessary only with regard to the shade of its shade. The shade that extends as far as the height of the tree is considered its shade. The less significant shade, that which extends further than the tree’s height, is referred to as the shade of its shade. The Mishnah is teaching that even this secondary shade is forbidden.

מכלל דבצל קומתה, אם ישב ⁠— טמא? לא, דאפילו לצל קומתה נמי, אם ישב ⁠— טהור, והא קא משמע לן, דאפילו לצל צילה לא ישב.

The Talmud comments: By inference, with regard to the shade of its height, its primary shade, if one sat there he is impure. The Talmud rejects this inference: No, this inference is not correct, as even with regard to the shade of its height, if one sat there he remains pure. And this is what the Mishnah is teaching us: That even with regard to the shade of its shade, one may not sit in it.

איכא דמתני לה אסיפא, ואם ישב טהור. פשיטא? אמר רבה בר בר חנה אמר רבי יוחנן: לא נצרכא אלא לצל קומתה. מכלל דלצל צילה אפילו לכתחלה ישב? לא, הא קא משמע לן, דאפילו לצל קומתה אם ישב ⁠— טהור.

There are those who teach this discussion with regard to the latter clause of that part of the Mishnah, which states: But if one sat in its shade he remains ritually pure. The Talmud asks: Isn’t this obvious? Why should he be rendered impure? Rabba bar bar Ḥana said that R' Yoḥanan said: It is necessary only with regard to the direct shade of its height. Even in this case, he remains pure. The Talmud comments: By inference, with regard to the shade of its shade, one may even sit there ab initio. The Talmud answers: No, this inference is not correct. Rather, this is what the Mishnah is teaching us: That even with regard to the shade of its height, if one sat there he remains pure.