Yesterday, we noted the view taken by some Rishonim requiring festivity on Purim Katan – the 14th and 15th days of Adar Rishon. This view is cited (and subsequently rejected) by Tosefot, in Masekhet Megilla (6b), who note that this is the implication of the Mishna, which states that the only difference between Adar Rishon and Adar Sheni is the obligations of Megilla reading and matanot la-evyonim (gifts to the poor). It appears that only these obligations do not apply on Adar Rishon, but the other obligations, such as feasting, do.
The Sefat Emet (commentary to Masekhet Megilla) proposes a novel reading of the Mishna that yields a much different halakhic conclusion. He suggests that the Mishna refers only to situations of be-di’avad – after the fact, if a person observed the Purim obligations on Adar Rishon, which we are not meant to do. When the Mishna rules, “There is no difference between the first Adar and the second Adar except Megilla and matanot la-evyonim,” it means that when it comes to the other Purim obligations, one who performs the given mitzva on Adar Rishon has fulfilled his obligation. Certainly, however, according to the Sefat Emet’s reading, the mitzvot should all optimally be observed in Adar Sheni. The Mishna speaks only of one who mistakenly performed the mitzvot in Adar Rishon, but presumes that they should optimally be observed only in Adar Sheni.
The basis for the Sefat Emet’s reading is the Gemara’s discussion of the Mishna, which begins by making a comment relevant to the arba parashiyot – the four special Torah readings conducted starting on the Shabbat before Adar. As the Mishna implies that there halakhic parity between Adar Rishon and Adar Sheni, the Gemara suggests that a congregation that mistakenly read the arba parashiyot in Adar Rishon has fulfilled its obligation. Leaving aside the Gemara’s conclusion, this comment would seem to indicate the Gemara understood the Mishna as speaking specifically of situations of be-di’avad, where a Purim observance was conducted in Adar Rishon. Optimally, however, it is clear that all observances should take place only during Adar Sheni.
On this basis, the Sefat Emet suggests that in terms of practical halakha, one specifically should not have a feast on Purim Katan. If he does, then he fulfills the annual obligation of feasting on Purim, and thus forfeits the optimal mitzva, which is to feast on Purim in Adar Sheni. This novel suggestion runs in opposition to the ruling of the Rama, in his final comments in the Orach Chayim section of the Shulchan Arukh, that it is proper to indulge a bit on Purim Katan.
As noted by Rav Asher Weiss, the Sefat Emet’s novel reading of the Mishna is not offered by other commentators and clearly has not been accepted.