Before us is Mishnah 1 in the fourth chapter of Tractate Sheviis. The Mishnah deals with gathering wood, stones and grasses from a field during the Shemittah year, and with the stages of the enactments that the Sages instituted in this matter because transgressors had become numerous.
"BaRishonah Hayu Omrim" - At first they would say:
The language of the Mishnah: "Melaket Adam Etzim Va'Avanim Va'Asavim MiToch Shelo, KeDerech SheHu Melaket MiToch Shel Chaveiro - Es HaGas HaGas" - a person may gather wood, stones and grasses from his own field just as he gathers from his fellow's field, taking only the coarse ones. By the basic law, a person was permitted during the Shemittah year to gather wood, stones and grasses from his field, just as he gathers from his fellow's field, provided that he take only the large ones among them.
The explanation of the Rishonim in the phrase "just as he gathers from his fellow's field":
In his fellow's field: He may gather both the large items and the small ones.
In his own field: Only the large ones - this is the meaning of "es hagas hagas" - but the small ones he does not gather.
The reason for permitting the gathering of only the large ones: when a person takes only the large items, it is evident and clear that his intention is for the wood, stones or grasses themselves, which he needs, and not in order to improve the field in preparation for planting.
"MishRabu Ovrei Aveirah" - When transgressors became numerous:
Once transgressors became numerous, gathering even the small items in their fields and claiming that these were nothing but the large ones, "Hiskinu SheYehei Zeh Melaket MiToch Shel Zeh, VeZeh Melaket MiToch Shel Zeh" - they enacted that this one should gather from that one's field, and that one from this one's field. A person does not gather from his own field, but from someone else's field. For when gathering from his own field, a person will come to gather even the small ones, and this was forbidden because it appears as though he is improving his field for planting, even though that is not his intention; but when gathering from his fellow's field, the matter does not appear as improving the field.
"SheLo BeTovah" - Not as a favor:
The Mishnah continues that the gathering from one's fellow's field is done "shelo betovah" - without crediting him with a favor and without expressing gratitude toward him. And some explain the matter to mean that there should be no arrangement between them of "I will do your field and you will do mine," but rather each one should gather in the fields of different people.
"VeEin Tzarich Lomar SheKatzatz Lahem Mezonos" - And it goes without saying that he set food for them:
All the more so: beyond the prohibition of crediting a favor and arranging a mutual exchange with one's fellow, there is certainly no permission to tell him that he will be given food or meals in return for performing the work. Setting a payment of food is not permitted at all.
An addition of the Rishonim - a further enactment:
The Rishonim add to our Mishnah that even after the enactment that a person should gather from someone else's field, the Sages suspected that people were gathering from other fields while claiming that it was done without favor and without a mutual arrangement, when in reality this was not so. Therefore they instituted a further enactment:
That he should not gather from anyone's field at all, but only "MiMana Karov U'MiMana Matzui" - things that are found in their homes and in the adjacent courtyard alone.
And some say that he should gather from ownerless material, in order to ensure that he will not come to prepare his fields for planting.
In summary: In this Mishnah we learned three stages in the laws of gathering wood, stones and grasses during Shemittah: by the basic law a person gathered from his field only the coarse items, for in this way it is evident that his intention is for the items themselves and not for improving the field; once transgressors became numerous and gathered even the small ones, they enacted that this one should gather from that one's field and not as a favor, and all the more so not with an arrangement of food payment; and afterward the Rishonim added an enactment that he should not gather from a field at all, but only from what is close and available in the house and courtyard, or from ownerless material - all so that he should not come to prepare his field for planting.