You’ve been warned, maybe TB Shabbat 138

We actually began the 20^th chapter of massechet Shabbat yesterday. The Mishnah on TB Shabbat 137 records a dispute between Rabbi Eliezer and the sages. “Rabbi Eliezer says: One may suspend and stretch over a base the strainer through which sediment is filtered from wine, on a Festival. And one may place wine through a strainer that was already suspended the day before; however, one may not suspend the strainer on Shabbat. And the Rabbis say: One may not suspend the strainer on a Festival, and one may not place wine for filtering through a suspended strainer on Shabbat; however, one may place wine through a suspended strainer on a Festival.” (Sefaria.org translation) Stretching a strainer over a container on Shabbat is violating the rabbinic prohibition of making a temporary roof (אוהל עראי). Indeed, the halakhah is in accordance with the sages; consequently, one is forbidden to suspend that strainer over a jar on a holiday as well as on Shabbat. (Shulkhan Arukh, Orekh Hayyim, 315:9, 319:9, and 410:4)

According to Jewish law ignorance is an excuse. Before a person is liable to bring a sin offering (חטאת) for accidentally violating the Shabbat, he needs to be warned that his actions are prohibited. On today’s daf TB Shabbat 138 Rabba and Rabbi Zeira disagree what forbidden labor (מלאכה) he is violating so that he may be warned correctly.

“The Gemara asks: One is liable to bring a sin-offering for straining. Due to performance of what category of prohibited labor do we forewarn him? Rabba said: It is for the category of selecting (בורר), as one is selecting the wine from the sediment. Rabbi Zeira said: It is for the category of sifting (מרקד), as straining is similar to sifting flour in a sifter, which is a form of selecting.

“Rabba said: According to my opinion, it is reasonable. What is the manner of one who selects? He takes the food and leaves the refuse; here too, when straining wine, one takes the food and leaves the refuse.

“Rabbi Zeira said: According to my opinion, that this is not typical selection but rather a specific type of selection, it is reasonable, as what is the manner of sifting? The refuse remains atop the sifter and the food is below. Here too, when straining wine, the refuse remains atop the strainer and the food is below.” (Sefaria.org translation)

Once again Rashi and Tosefot disagree on this sugiyah’s interpretation. Without knowing this disagreement, I believe we would come to the conclusion that sifting is the prohibited labor, malakhah (מלאכה). Rashi clarifies Rabba’s position. He interprets Rabba saying that selecting (בורר) works just as well as sifting (מרקד) for the purposes of the warning. Rabbi Zeira disagrees and believes that only sifting is the correct prohibited labor.

The Tosefot back on daf TB Shabbat 73b ד''ה משום זורע quoting our Gemara, interprets this disagreement differently. They hold the position that one does not need to specify the prohibited labor, malakhah (מלאכה), in the warning to be liable for a sin offering, חטאת . But if you do cite a prohibited labor, siding with Rabbi Zeira, you must use the correct malakhah. If you do not use the correct malakhah, the person is freed from the obligation (פטור) of bringing a sin sacrifice (חטאת) because he will think you are mocking him and not take the warning seriously.

I’m warning you that I don’t know whose interpretation is correct.