This is one of those daf that are  filled with an array of different colorful topics not directly related to Eruvin per se, spanning from other shabbos laws to advice regarding marital intimacy.

One of them is the prohibition of climbing or making use of trees on Shabbos and Yom-Tov.

The Gemara also brings a Beraisa that says that one may not even walk on grass on Shabbos, apparently in case one uproots it while walking.

This supports a ruling to that effect of Rami bar Aba in the name of Rav Assi, who bases this on the passuk )Mishlei 19/2)  “ואץ ברגלים חוטא”- one who is “אץ” with his legs is a sinner.

Rashi explains that this implies that walking can be considered a sin and doing so on grass on shabbos is precisely such a case.

The Gemara brings another Beraisa that rules to the contrary that walking on grass on shabbos is permitted.

The Gemara gives several options to reconcile these two Beraisa’s:

1. The stringent  Beraisa is talking about walking on moist grass, which Rashi explains is forbidden, whereas the other is talking about walking on dry grass which Rashi explains is considered as if it has already been uprooted. Perhaps this is because dry grass  does not grow, is no longer deriving much nourishment from the grounded and detaching it might thus not fall under the מלאכה  of קוצר (harvesting) which includes detaching anything from the place where it grows.
2. The one Beraisa is talking about during the dry season, and the other is talking about during the wet season.
3. The stringent  Beraisa is talking about someone who is not wearing shoes. Rashi explains that the grass gets stuck around his toes and is easily torn.
4. The stringent Beraisa is talking about one is who wearing shoes with nails in the bottom which cause grass to be torn .
5. The stringent Beraisa is talking about walking on long grass which is more easily uprooted.

Though there appear to be some differences in the גירסא  (wording) of the above distinctions, they seem to be conclusively rendered mute by the Gemara that concludes that “today” that we follow Rabbi Shimon who holds that דבר שאין מתכוין מותר, it is permitted under all the above circumstances.

We have discussed multiple times in our posts on Maseches Shabbos the rule of דבר שאין מתכוין- when an otherwise permitted action might result in an unintended  secondary forbidden action.

Although Rabbi Yehuda and the Amora Rav forbid such an action, Rabbi Shimon and the Amora Shmuel permit it, and many Amoraim rule accordingly, including the later authority Rabbah- one of the only 3 times he supports a leniency of Shmuel against a stringency of Rav.

In our case, one wishes to perform the ostensibly permitted action of walking on grass, and there is a concern that while doing so, one will unintentionally transgress a second forbidden action of uprooting the grass

As we also know from various places, when the secondary forbidden action is inevitable, it is known as פסיק רישיה  and even Rabbi Shimon forbids the otherwise permitted action .

As such, it should follow from our Gemara’s application of Rabbi Shimon’s leniency to walking over grass in all these different circumstances that it does not consider uprooting the grass to be an inevitable result even when the shoes have nails in them or where the grass is long! (Alternatively, this could serve as a proof for the view of the ערוך who permits פסיק רישיה דלא ניחה but that is for a different discussion!)

If so, it seems that Rami bar Aba and Rav Assi who applied the passuk in Mishlei to this act, in line with the stringent Beraisa, must have held like Rabbi Yehuda and his view and accompanying דרשה  from the passuk is rejected together with the stringent Beraisa.

A very practical question involves whether this lenient ruling applies to running on grass as well.

On the one hand, the pressure exerted by running on the grass is certainly greater than that exerted by walking, both because of the speed as well as the different mechanism of running.

On the other hand, it is certainly not clear that running on short grass with regular shoes is more likely to uproot the grass than running on long grass with nailed shoes, and if the later is not considered פסיק רישיה, the former might not be either.

In addition, if there was a distinction between walking and running, one would expect the Gemara to make that distinction- it would be a perfect way to reconcile the two Beraisa’s!

One might counter that running is already forbidden on Shabbos as a weekday activity (see Shabbos 113a) but running  to learn, shul  or for the sake of another  mitzva is permitted (see Brachos 6b and Rif’s girsa there) , as is running for עונג שבת   (סמ”ק רפא) , so that argument seems rather mute.

If it was indeed פסיק רישיה  to run on grass on the way to shul, for example, one would expect the Gemara to say so at some point.

The Biur Halacha (O.C. 336/3) however, brings the סמ”ג  (לאוין סה) , who quotes the Yere’im as bringing our Gemara as a proof that one should not walk on grass on shabbos where it is impossible not to uproot it while walking!

He quotes others who questioned these words of the סמ”ג  based on the seemingly obvious fact that the Gemara rejected the view that forbids walking on grass because we follow Rabbi Shimon, implying that it does not consider it to be פסיק רישיה  under any circumstances- after all, this is how most of the Rishonim seem to have learnt the sugya!

He suggests that the סמ”ג  and יראים were bothered by the fact that the Gemara rejected all the distinctions made to reconcile the stringent Beraita with the lenient one, because we follow Rabbi Shimon, but did not reject the derasha of Rabbi Assi that started the discussion.

They therefore assume that Rabbi Asi’s derasha is still upheld and he must be referring to running on tall grass, which is considered to be  פסיק רישיה.

Based on this reasoning, he cautions in  the Mishna Berura (O.C. 336/25)  against running on long grass on Shabbos.

This seems to be quite a chumra, given that it is based on a distinction not made by the Gemara, as well as a novel interpretation of a סמ”ג  and יראים  that we do not see in most of the Rishonim (see Aruch haShulchan 336/21 who indeed rejects this stringency for these reasons,) but it opens the door to the possibility that under certain circumstances, there is a distinction between running and walking, and even when running is permitted on shabbos, for a mitzva or oneg shabbos, it might be problematic where uprooting the grass appears closer to inevitable.

Would the Mishna Berura extend that stringency to other types of running that might be closer to פסיק רישיה  such as running on regular grass without shoes or with nail-studded shoes?

Seeing as his ruling is already novel, and he never mentioned such obvious possibilities, it seems that even if we follow his stringency, we should apply the rule of אין בו אלא חדושו (we do not extend a novelty beyond what is stated,) unless it is clear to us under certain circumstances that there is a case of פסיק רישיה.

These posts are intended to raise issues and stimulate further research and discussion on contemporary topics related to the daf. They are not intended as psak halacha