Bava Metzia, Chapter 9, Mishnah 5. This Mishnah also deals with someone who receives a field from another, but here we are dealing with arisus (sharecropping) - the tenant receives a percentage of the crop, according to a fixed division agreed upon between the parties. The problem is that for some reason the field does not produce grain that year: perhaps due to poor weather conditions or something similar. Therefore, the sharecropper is not interested in working, claiming that the whole enterprise is just a waste of time - a lot of work and zero output. But the landowner is supposed to receive fifty percent of the output, and is losing out. The question is therefore: Is the landowner allowed to force the sharecropper to work, even though it does not pay off for the sharecropper? After all, for the landowner, it certainly pays off: he does not invest any work at all, and receives some return.
The language of the Mishnah:
"Hamekabel sadeh mechaveiro velo astah" - A farmer who received a field to cultivate through sharecropping, and the field did not produce grain, or produced very little.
"Im yesh bah kedei leha'amid keri" - If grain grew in an amount sufficient to set up a pile, meaning that after gathering the wheat, threshing it, and winnowing it, a pile of grain remains. Its measure, according to the Bartenura, is about two se'ah (satayim), which is about seventy-two liters. The sign of this pile is that it is large enough that the pitchfork used for winnowing can be stuck into it, and it will stand in it.
"Chayav letapel bah" - The sharecropper is obligated to cultivate the field.
The reason for this: Even though the sharecropper receives very little for a lot of work, the grain is not completely worthless, and the landowner can say: It is significant in my eyes, and I am not willing to give it up.
The opinion of Rabbi Yehudah:
Rabbi Yehudah questions this ruling: It is one thing for a small field that produces a little, but what is the law for a massive field that only produces one small pile of grain? This results in an enormous amount of work for a meager output, and it is not fair. Therefore, Rabbi Yehudah says: "Mah kitzvah bekeri?" - What is the reason to set an arbitrary and absolute amount, like one pile of grain? Such a measure can be completely ridiculous in a giant field.
"Ela im yesh bo kedei nefilah" - In his opinion, the measure is relative: if the field can return the amount of grain that was invested in it. "Nefilah" means what falls into the ground, that is, the amount sown. For in sowing a field, wheat kernels are taken and hidden in the earth, and more wheat kernels come out of the earth. It turns out that if the net calculation yields at least the amount that was put in, it is not a losing enterprise, and the sharecropper is obligated to work. But if the output is less than this, and it is indeed a losing enterprise, we do not force the farmer to work, as there is no logic in doing so.
The halachah: The halachah does not follow Rabbi Yehudah, but rather the Tanna Kamma: If the field can produce one pile, in the measure of satayim or something similar, it is incumbent upon the sharecropper to do his best so that it produces as much as possible, and the two parties will divide the crop according to the original agreement between them.