In the Book of Leviticus, God commands the Jewish people to let their lands lie fallow every seventh year. Fields should not be sown, vineyards should not be pruned, and the land should be allowed to rest. This mitzvah is known as shmita, the sabbatical year, and any produce that grows spontaneously in that time is hefker — ownerless and available for the taking.
The discussion on today’s daf is about the status of a vow that is made either just before or during the sabbatical year, termed here as shevi’it (literally, seventh).
The mishnah reads:
If one vowed before the sabbatical year (that benefit from another person’s) food (is forbidden for him), he may enter his field; however, he may not eat of the produce. And during the sabbatical year, he may enter the field and may eat the produce.
On Nedarim 16, we learned that one cannot vow not to do a mitzvah, and if one makes such a vow, the vow is automatically nullified. The mishnah seems to say that is the case here as well. If a person is prohibited by vow not to benefit from someone else’s food, in the sabbatical year he may nevertheless enter that person’s field and eat their produce, since in the seventh year the field’s produce must be available to all and therefore it’s not off-limits despite the vow.
Does the Gemara agree? That depends.
Rav and Shmuel both say (that if one vowed) before the sabbatical year (benefit from) this property (is forbidden) to you, (the other) may neither enter his field, nor eat from (the produce) that leans (out of the field), even though the sabbatical year arrived.
According to Rav and Shmuel, a vow that was made before the seventh year is still in effect even during the sabbatical year. Produce that leans out of the field, and would normally be free for anyone to take, is still prohibited on account of the vow.
Rabbi Yohanan and Reish Lakish disagree.
(If one vowed) before the sabbatical year, my property (is forbidden) to you, the other may neither enter his field nor eat from (the produce that leans out of the field). When the sabbatical year arrives, he may not enter his field; however, he may eat from (the produce that leans out of the field).
Reish Lakish and Rabbi Yohanan rule that a person prohibited by a vow made prior to the sabbatical year from benefiting from their neighbor’s food still cannot enter the neighbor’s field once the sabbatical year begins. However they can eat produce that hangs over the edge of the field, the logic being that the produce no longer belongs to the neighbor and so the vow prohibiting it no longer applies.
The Gemara identifies the core of the disagreement:
Rav and Shmuel hold: A person can render an item in his possession forbidden, and the prohibition remains in effect even when it leaves his possession.
And Rabbi Yohanan and Reish Lakish hold: A person cannot render an item in his possession forbidden and have the prohibition remain in effect when it leaves his possession.
Essentially, the disagreement hinges on whether the rendering of a person’s field ownerless by the onset of the sabbatical year negates a vow prohibiting someone from benefiting from that field’s produce. Rav and Shmuel say the vow remains in effect, while Rabbi Yohanan and Reish Lakish say it doesn’t. So can a person who makes a vow not to benefit from a neighbor’s field still eat the produce inside or outside the gate during the sabbatical year? The Gemara doesn’t tell us.
Thankfully, many centuries later, Maimonides gives us some practical guidance.
“It is forbidden for Reuven to partake of the produce of Shimon’s field, even during the sabbatical year when everything is ownerless, for he took the vow before the beginning of the sabbatical year. If he took the vow in the sabbatical year itself, [Reuven] may partake of the produce that hangs outside the field. He may not, however, enter the field even though the land is ownerless.” (Mishneh Torah, Vows 6:13)
Today, the mitzvah of the sabbatical year is still observed in Israel. While some farmers do in fact allow their land to lie completely fallow, others use creative halachic workarounds, such as selling their fields to non-Jewish growers to manage during the year or setting up automatic hydroponic watering systems so that machines rather than humans are working the land. These laws remind us that the earth belongs to God, not humans. And as Dvora Waysman has observed, it periodically liberates us from the obligation to work the land, freeing us up for other pursuits — like Torah study.
Read all of Nedarim 42 on Sefaria.