(Mishnah) Question: Until when may one plow a field of trees before Sheviis?

Answer: Beis Shammai say - as long as it is beneficial to the (6th year) fruit. Beis Hillel say - until Shavuos. These two opinions are close (in time).

(Gemara): (The Mishnah taught that one may not plow before Sheviis. What is the source for this?) The pasuk states (Shemos 23:12), "You shall do you work for six days and on the seventh day you shall rest"; and the pasuk states (Shemos 34:21), "You shall rest from plowing and harvesting". What's the case?

If it's referring to Shabbos Bereishis (a reference to keeping Shabbos each week), another pasuk already states (Shemos 20:9), "Six days you shall work and do all of your creative work"? If it's referring to Sheviis, another pasuk already says (Vayikra 25:3), "Six years you shall sow your field and six years you shall prune your vineyard..."

If it isn't referring to Shabbos Bereishis, nor to Sheviis, it must be referring to the two times taught later on (fields of trees have a certain required time to stop and grain fields have another) - i.e. Tosefes Sheviis (adding on before and after Sheviis) - "You shall rest from plowing and harvesting" - means that you should rest from the plowing whose later harvesting is prohibited - which is plowing before Sheviis. And that harvesting refers to harvesting whose plowing had been prohibited - which is plowing on Motzei Sheviis. (The Chachamim applied the pasuk by setting the exact limits of the prohibition, as detailed later in the Maseches.)

Question: If so, why does a Tosefta say that one may plow until Rosh Hashana?

Answer (R. Kruspai citing R. Yochanan): Rabban Gamliel and his Beis Din permitted the prohibition of the two times that the Chachamim set.

Question (R. Yochanan): Wasn't it taught that a Beis Din cannot annul the ruling of another Beis Din unless they are greater than it in wisdom and number?

Answer (R. Krospi citing R. Yochanan): The original Beis Din taught the law on condition that a later Beis Din could annul it and plow when needed.

Question: If so, remove the prohibition from the Mishnah?

Answer (R. Krispa citing R. Yochanan): So that if they would need to bring the law back, they would be able to do so.

Question (R. Yona): What about the Parsha of the Miluim (the inauguration of the Mishkan) and the Parsha of the Flood - they won't return, so why not remove them from the Mishnah? Rather, it is to inform you of what happened and so too with the original Sheviis prohibition.

Reason #2 (R. Mana): It's like the Mishnah (in Maseches Eduyos) - (If the Halacha follows the majority, why was the minority opinion mentioned?) So that if someone will say that he heard different to the Halacha, tell him that it was according the minority opinion (but the Halacha doesn't follow it). Similarly, if someone says that they heard that one may not plow all the way up until Rosh Hashana, tell him that he heard about the original prohibition of the two times set by the Chachamim (but the Halacha is not that way).

(R. Acha citing R. Yonasan): (A further reason as to how Rabban Gamliel permitted the prohibition - answering R. Yochanan's earlier question (f)) When they prohibited Tosefes Sheviis, they relied on a pasuk and when they permitted it, they also relied on a pasuk - to prohibit they relied on (Shemos 34:21), "You shall rest from plowing and harvesting" - that refers to a plowing whose harvesting is prohibited, meaning of Erev Sheviis; and it refers to a harvesting whose plowing was prohibited, meaning of Motzai Sheviis.

And when they permitted it, they relied on the pasuk (Shemos 20:9), "Six days you shall work and do all of your creative work". Just as before Shabbos Bereishis you may do work until sunset, so too before Sheviis, you may do work until sunset (at the onset of Rosh Hashana).

Question: Why did Beis Hillel permit plowing until Shavuos?

Answer: Until then it's beneficial to the current crops, but after that it's damaging (so it is then becomes clear that he is plowing for the 7th year).

Rebuttal: But the (later) Mishnah taught that the law applies both to a non-fruit bearing and a fruit bearing tree...?

Answer: Rather, Beis Hillel say that until Shavuos, plowing causes the trunk to thicken (which makes them suitable to cut for beams), but plowing after that weakens the tree's roots (so he can't be doing it for the 6th year).

Question: If it's damaging, why stop him from plowing after Shavuos?

Answer: Since he knows this, he must be doing it to work the land for Sheviis.

Question: Why wasn't this Mishnah taught amongst the cases where Beis Shammai are lenient and Beis Hillel are stringent?

Answer: It isn't always that way - sometimes there is a shortage of rain and the earth is already dried out before Shavuos, so according to Beis Shammai, he must stop plowing then, since it won't benefit the 6th year; however, Beis Hillel would still allow plowing until Shavuos.