Shevi'is, Chapter 2, Mishnah 5. This mishnah deals with a process that was done to figs that had not yet ripened (unripe figs): they would smear them with oil and pierce holes in them, so that the oil would penetrate and hasten their ripening.
Smearing and piercing unripe figs of the year before Shevi'is:
It is permitted to smear oil on unripe figs and to pierce holes in them so that the oil will enter and help them ripen, and this may be done up until Rosh Hashanah. There is no problem at all with this activity.
Two categories in which smearing and piercing were forbidden:
Unripe figs of the year before Shevi'is that carried over into Shevi'is: figs that do not ripen before Rosh Hashanah like the first category, but only during Shevi'is itself. One may not smear them with oil or pierce them, for whoever does so derives benefit and performs work for the sake of Shevi'is produce, something he is not permitted to do, since these are Shevi'is fruits.
Unripe figs of Shevi'is that carried over into the year after Shevi'is: figs that began to grow during Shevi'is and ripen only afterward. With these too one does not smear and does not pierce, because they carry the sanctity of Shevi'is, and with fruits that carry the sanctity of Shevi'is one may not perform various processes but may only eat them.
The view of Rabbi Yehudah - it all depends on local custom:
A place where the custom is to smear: one does not smear, because there smearing is considered work. Therefore, with unripe figs that will ripen only during Shevi'is, smearing them with oil is considered work performed on Shevi'is produce.
A place where the custom is not to smear: one may smear, since there smearing is not considered work but merely an incidental act.
However, this distinction of Rabbi Yehudah, which depends on custom, applies only to fruits of the year before Shevi'is that carry over into Shevi'is, where the question is whether the act counts as work forbidden with Shevi'is produce. But with fruits that grew during Shevi'is itself the issue is not relevant: the question there is not the performance of work during Shemittah, but whether a person is treating the fruits properly in light of the sanctity of Shevi'is. With these fruits the limit is set by the sanctity of Shevi'is, and therefore one may not do this in any case, and it makes no difference whether the custom is to smear or whether smearing is considered work.
"Rabbi Shimon matir ba'ilan": - Rabbi Shimon permits it with the tree.
Rabbi Shimon holds that it is permitted to perform work on the tree itself in the year after Shevi'is. Even though fruits subject to the laws of the sanctity of Shevi'is are attached to it, working the tree is permitted, since whoever does so is dealing with the tree, and this does not affect the sanctity of Shevi'is in the fruits. In the year after Shevi'is the laws of performing work during Shevi'is are no longer relevant, and while the sanctity of Shevi'is does indeed apply to the fruits, here one is not dealing with the fruits directly but only with the tree.
In summary: in this mishnah we learned that smearing unripe figs with oil and piercing them, done in order to hasten their ripening, are permitted with unripe figs of the year before Shevi'is up until Rosh Hashanah. Two categories were forbidden: unripe figs of the year before Shevi'is that carried over into Shevi'is, because the act counts as work and as deriving benefit for the sake of Shevi'is produce; and unripe figs of Shevi'is that carried over into the year after Shevi'is, because of the sanctity of Shevi'is in them, which permits nothing but eating. Rabbi Yehudah made the matter depend on local custom, but only with fruits of the year before Shevi'is that carried over into Shevi'is. And Rabbi Shimon permits work on the tree itself in the year after Shevi'is, since one is dealing with the tree and not with the fruits.