Shevi'is, Chapter 1, Mishnah 4. In the two previous mishnayos we learned that three trees are required, each capable of producing a kikar develah - a cake of pressed figs weighing sixty maneh - in order for the field to be classified as a tree field, permitting one to plow all of it until Shavuos. Our mishnah comes to discuss a case in which not all of the trees meet this requirement.
Trees whose yield is not equal:
"Hayah echad oseh kikar develah u'shnayim ein osin" - one of the three trees is capable of producing the measure of a cake of pressed figs, while two of them are not capable.
"O shnayim osin ve'echad eino oseh" - two of them are capable and one is not capable.
In both of these cases the ruling is "Ein choresh ela l'tzorchan" - as was explained in the previous mishnah, one may plow in such a field only the area surrounding each individual tree: the space needed for the person picking the figs and for the basket that goes along with him.
The description "one produces a cake of pressed figs and two do not" is understood in two ways, following the two approaches explained above:
The measure is divided among the three trees - one of them is capable of producing its third, and two are not capable of producing their thirds.
Each one of the trees must produce a full cake of pressed figs - one is capable of producing a cake of pressed figs, and two are not capable.
From ten trees and upward:
All of the above, that the trees must be capable of producing the measure in order to be considered proper fruit trees and to classify the field as a tree field that may be plowed until Shavuos, applies specifically "Mishloshah ve'ad tishah" - that is, in a field containing between three and nine trees. But "Hayu eser, me'eser ulmalah, bein osin bein she'einan osin - choresh kol beis se'ah bishvilan": once there are ten trees or more, whether they are capable of producing the measure or not, one may plow the entire beis se'ah, the whole area of the field, for the sake of these trees, simply because it contains ten trees.
The source for the prohibition of plowing on the eve of the Shemittah year:
From here the mishnah moves on to a new subject, even though its wording sounds like a continuation of what came before: until now we dealt with the prohibition of plowing on the eve of the Shemittah year, and now the mishnah seeks to clarify the source of this prohibition. The mishnah says: "Shene'emar: becharish uvakatzir tishbos" - this verse is actually stated in the passage dealing with Shabbos, not in the passage dealing with Shemittah, and it teaches the obligation to refrain from plowing and from harvesting.
Chazal understood that the verse cannot be referring to Shabbos, for regarding Shabbos it has already been stated that no work whatsoever may be done - so why single out plowing and harvesting when all forms of work are forbidden? They therefore expounded that the verse is not referring to Shabbos at all, but rather to the Shemittah year.
And even though the verse refers to Shemittah, the mishnah notes: "Ein tzarich lomar charish v'katzir shel shemittah" - there is no need to teach us not to plow and not to harvest during the Shemittah year itself, since other verses have already addressed that. Rather:
"Ela charish shel erev shemittah shenichnas bashemittah" - the verse comes to teach us that it is forbidden to plow on the eve of the Shemittah year, because such plowing benefits the Shemittah year.
"V'katzir shel shemittah shehu yotzei l'motzaei shemittah" - and likewise that it is forbidden to harvest the produce of the seventh year when that harvest extends into the year following Shemittah.
It emerges that one must add on to the Shemittah year at its beginning and at its end - an addition to the seventh year before it and after it - although our mishnayos do not discuss this point at present.
The opinion of Rabbi Yishmael:
Rabbi Yishmael disagrees and holds that the verse is speaking about Shabbos, according to its plain meaning and its straightforward reading. But according to his approach as well, the question arises: what need is there to state that these two forms of work may not be done on Shabbos, when all forms of work are forbidden on Shabbos? Rabbi Yishmael therefore expounds the verse differently: the verse teaches a comparison between plowing and harvesting - "Mah charish reshus, af katzir reshus". Just as plowing is always an optional act, since there is no mitzvah in the Torah that obligates one to plow, so too, when the Torah forbade harvesting on Shabbos, it forbade only optional harvesting.
It follows from this that the verse comes to exclude the harvesting of the Omer: the Omer must be reaped on the night of the sixteenth of Nissan, in order to bring the Omer offering during the following day, and even if that night falls on Shabbos, it is permitted to reap it, since this is not optional harvesting but harvesting for the sake of a mitzvah. Just as plowing is forbidden only when it is optional, so too harvesting is forbidden only when it is optional, and consequently the reaping of the Omer is permitted on Shabbos.
In summary: In this mishnah we learned that in a field containing between three and nine trees, if not all of them meet the measure of a cake of pressed figs, one may plow only for their needs, the area surrounding each tree; and from ten trees and upward one may plow the entire beis se'ah for their sake, whether they produce the measure or not. We also examined the source for the prohibition of plowing on the eve of the seventh year from the verse "becharish uvakatzir tishbos," and the opinion of Rabbi Yishmael, who derives from this verse the comparison between plowing and harvesting, teaching that the reaping of the Omer is permitted on Shabbos.