Brochas Daf Yud Aleph amud aleph

Tani d'Bei Rav Yehezkel …

Beis Shamai hold that the evening Shema can only be recited lying down; Beis Hillel that it can be recited in any position.  Rav Yehezkel holds that one who acts like Beis Shamai has fulfilled the mitzva; Rav Yosef holds that to the degree he has the kevana to act like Beis Shamai, he has not, and cites as a proof a Brysa from Gemara Succah (daf gimmel): a man sitting with his head and the majority of his body inside the succah, but with his table outside it, has fulfilled the mizva of eating in the succah according to Beis Hillel but not according to Beis Shamai.  Beis Hillel seek to prove their position by recounting an incident when R. Yochanan be HaChoranis acted in this fashion and the rabbis did not upbraid him. Beis Shamai retort that in fact the elders of Beis Shamai told him that if this was the way in which he had always acted, he had never fulfilled the mitzva of succah.

One of the issues identified as problematic with this Gemara is that Rav Yosef holds that that if one recites the evening Shema while reclining, but does so intending to fulfil the mitzva according to Beis Shamai, then surprisingly one is deemed not to have fulfilled the mitzva at all, even though acting in this fashion constitutes a practice which brings one within the ambit of the mitzva as constituted by Beis Hillel.  In other words even though the stricter standard of Beis Shamai should be acceptable to Beis Hillel, it is deemed not to be. Given this, citing Gemara Succah as a proof text seems untenable, because in that case, unlike in our Gemara, there would seem to be no overlap in the positions of Beis Hillel and Beis Shamai and therefore no reasonable expectation that Beis Shamai would agree to that eating with the table outside the succah constitutes performance of the mitzva.

In fact, Gemara Succah is an appropriate comparison, because where the succah is sufficiently large to encompass a table, but the table is in instead placed outside, Beis Shamai hold (in contra-distinction to Beis Hillel) that because the person may lean out of the succah to eat, he renders an otherwise kosher succah invalid even when he does not in fact lean outside the succah.  The two Gemaras are therefore analogous, since in both the protagonist is currently acting in a manner which should be held acceptable, but is deemed unacceptable.

Interestingly, the Pnei Yehoshua points out that according to Gemara Yevamos (daf Tes Zayin) R. Yochanan ben HaChoranis was a talmid of Beis Shamai (and perhaps that was why Beis Hillel cited him in particular).  Nonetheless, because the Halacha is that we hold like Beis Hillel, he deliberately ate with his table outside the succah to demonstrate that he subordinated himself to the Halacha, not only where the positions of Beis Hillel and Shamia overlapped, but in a case such as this where they did not.