The ninth perek of Massekhet Bava Metzia, which is entitled hamekabel sadeh me-havero – “Someone who receives a field from his friend” – began on yesterday’s daf and its focus is the relationship between the owner of a field and the person who commits to working the field.
Ordinarily, someone who gives a field to his friend does so with the expectation that the recipient of the field will plow, seed and harvest the field, and that they will share the produce based on some agreed-upon formula. The Mishna on today’s daf teaches that if the recipient of the field leaves it barren, the courts will estimate how much the field should have produced, and he will have to pay that amount to the owner. The Mishna explains that this is based on the agreement which states “if I leave the field barren and do not work it, I will pay the full value.”
One of the questions raised by the commentaries is why the Mishna needs to teach us this rule. Clearly, if a condition like that is agreed upon and is written into an agreement, the parties involved will have to keep it.
Rabbeinu Hananel explains that the condition written in the agreement is not written appropriately, that is, it does not follow the regulations derived from the negotiations between the tribes of Re’uven and Gad with Moshe that appears in Sefer Bamidbar (chapter 32) – see Kiddushin 61 for details on the rules of tenai b’nai Gad and b’nai Re’uven. Furthermore, there is an element of asmakhta – an assumption made by the recipient that he will never have to pay the penalty, since he is certain that the circumstances will never come to pass, i.e. he is certain that he will work the field. Generally speaking we rule that asmakhta lo kanya – when someone agrees to a condition because he is certain that it will never come to pass, the agreement does not take effect.
Many commentaries explain otherwise, arguing that the Mishna should not be taken literally, and that this rule applies even if the agreement was not clearly written into the contract, if that was common practice in that community.