In a case where Reuven sells Shimon a Beis Kur 'be'Simanav u'vi'Metzarav', our Mishnah rules 'Pachos mi'Shetus Higi'o, ad Sh'tus Yenakeh'. Thirty Kabin comprise a sixth, in a field of a Kur (four times as much as a Rova ha'Kav le'Beis-Sa'ah.

The reason for this is - because having shown the purchaser the borders of the field, it is as if the seller stipulated that the sale is valid as is. On the other hand, it must be close to the Beis-Kur that he stipulated. So Chazal (based on their assessment of how much a person tends to be Mochel) struck the balance in this way.

This ruling can have nothing to do with the Din of Ona'ah - due to the principle 'Ein Ona'ah le'Karka'os' (Karka is not subject to Ona'ah).

Its source is - a Takanas Chachamim, based on the Chachamim's assessment of how much a person tends to be Mochel (as we just explained).

The Seifa of the Mishnah 'ad Shtus, Yenakeh' means that - if the discrepancy entails 'as much as a sixth' less than what Reuven promised Shimon, then the latter deducts the balance from the price.

According to Rav Huna, 'Sh'tus ke'Pachos mi'Shtus', and the purchaser must accept the sale. Rav Yehudah holds - 'Sh'tus ke'Yoser mi'Shetus'.

Based on the Seifa of the Mishnah ('ad Sh'tus Yenakeh'), the basis of their Machlokes is whether we hold 'ad ve'ad bi'Chelal' (Rav Yehudah) or 'ad ve'Lo ad bi'Chelal' (Rav Huna).

Rav Huna explains the Mishnah like this ' ... Pachos mi'Shetus (u'Shetus bi'Chelal) Higi'o; Yoser mi'Shetus Yenakeh'.

The Beraisa repeats the Lashon of our Mishnah, but adds (' ... O Hosir Sh'tus, Harei hu ke'Shum ha'Dayanim' - where Beis-Din assess the property of Yesomim to sell, to use the proceeds to sustain the deceased's widow and daughters.

If the Beis-Din erred by exactly a sixth - their ruling is disqualified as if they had erred by more than a sixth ...

... a Kashya on Rav Huna, who equates the Din of a sixth with that of less than a sixth.

Rav Huna counters the above Kashya based on the Tana's insertion of the word 'Higi'o' whereas in the Seifa, in the case of 'Yoser mi'Shetus' (and of 'Sh'tus', according to Rav Yehudah), he ought to have said 'Yenakeh'?

Rav Huna therefore explains that the Tana is only making a partial comparison to a regular Shum ha'Dayanim, but in other ways, it is not like Shum ha'Dayanim. 'ke'Shum ha'Dayanim' applies - only with respect to the Shi'ur of error of a sale 'be'Simanav u'vi'Metzarav', which is one sixth (thirty Kabin per Kur), as opposed to a regular sale, where the Shi'ur of error is seven and a half Kabin per Kur.

And it is not like Shum ha'Dayanim - in that 'Shum ha'Dayanim the ruling is Bitul Mekach, whereas here it is 'Higi'o'.

A man told Rav Papa, that the field he was selling him measured twenty Se'ah. The actual measurements of the field were fifteen Se'ah.

Abaye ruled that, despite the fact that that the discrepancy was more than a sixth, since Rav Papa had thought it over and accepted it, the sale was not retractable.

This case differed from 'be'Simanav u'vi'Metzarav' in our Mishnah - inasmuch as Rav Papa was aware from the outset that the field measured only fifteen Sa'ah.

Rav Papa queried Abaye's ruling by claiming that - the owner was unaware of the field's measurements, and that he only mentioned twenty Se'ah having in mind that if it measured less, he would either give him the balance, or deduct from the price.

Abaye overruled his objection however, by pointing out that the owner really did know the true size of the field, and he only said twenty Se'ah to boost his sale (as if to say that it was as good as another field of twenty Se'ah), in the way that salesmen tend to do.

Rebbi Yossi says in a Beraisa 'ha'Achin she'Chalku, Keyvan she'Alah Goral le'Echad Meihen, Kanu Kulam' They are not required to make a Kinyan in order to actually acquire their respective portions - because the property already belongs to them ...

... and the purpose of the Goral is merely - to clarify which portion each one will receive.

The brothers did not plan to apportion the property - because Rebbi Yossi is speaking where the property has already been divided into equal portions.

R. Yossi meant, assuming that there were ...

... only two brothers to begin with that - when the one acquires his portion through the lottery, his brother will automatically acquire the remaining portion.

... three brothers to begin with that when the one acquires his portion through, the other two will acquire the remaining two portions between them, to divide them when and as they see fit.

The ramifications of this ruling are that - the moment the first brother receives his portion, none of the brothers are permitted to retract from whatever they have at that moment (something that they were able to do before the first brother drew lots).

The source that Rebbi Elazar cites for Rebbi Yossi's ruling is - the distribution of Eretz Yisrael in the time of Yehoshua, which was apportioned by lots.

In order to inherit Eretz Yisrael, they also required - a box (for the lots) and the Urim ve'Tumim (the Choshen Mishpat, with Names of Hash-m inside the folds).

Rav Ashi explains that (despite the fact that the source for the current Halachos is the inheritance of Eretz Yisrael) these two items are not required by brothers or partners dividing their land - because the deal is clinched instead by the pleasure that each brother derives from the mutual trust between them (in return for which he is Makneh his brother his portion, as if the Urim ve'Tumim was present).

According to Rav, if, after the first two brothers have divided their inheritance of Karka, a third brother arrives from overseas, the original division is considered invalid, and they divide their property afresh, unlike the previous ruling (where, as soon as the first brother acquires his portion, the remaining brothers automatically acquire theirs) - because whereas there, the first brother only took what was his, here the two brothers took more than their due.

Shmuel disagrees with Rav. When he says 'Mekamtzin', he means that - each brother deducts a third of what he received (e.g. one out of his three fields), and gives it to the third brother without the need to redistribute the property.

Rava remarked to Rav Nachman that Rav holds 'Hadar Dina' which means that - if some of the partners or brothers divide the property without the consent of the others, their transaction is invalid.

When he asked him why it does not then follow, that if two out of three brothers went and divided the joint property into three portions in front of Beis-Din, the division will also be invalid, Rav Nachman replied that there the division would be valid - because they initially divided the property into three portions (in which case, the division stands), unlike in the case of Rav, where they initially divided it into only two portions instead of three.

To effect such a division - even a Beis-Din of Hedyotos (laymen [i.e. any three Kosher Jews]) will suffice.

Rav Papa remarked to Abaye that Shmuel, who rules 'Mekamtzin', holds 'Kam Dina', which means that - if some of the partners or brothers divide the property, even without the consent of the others, their transaction is valid (Bedi'eved).

This seems to clash with Shmuel's other ruling (discussed earlier) 'Kur bi'Sheloshim Ani Mocher lach, Yachol la'Chezor bo Afilu be'Se'ah Acharonah' inasmuch as there too, we ought to apply 'Kam Dina' (and declare the transaction valid Se'ah by Se'ah, as he pours it into his jars)?

We reconcile that ruling with Shmuel's current one however - by ascribing the ruling there to a Takanas Chachamim, which is to the advantage of both parties; the purchaser is happy to be able to retract in the event that the price of the goods drops, whereas the seller is pleased with the chance to retract in the event that the price rises.

Nevertheless, Shmuel concluded 'Kur bi'Sheloshim Se'ah be'Sela Ani Mocher lach, Rishon Rishon Kanah' - because there, the purchaser acquires each Se'ah with Meshichah, finalizing the deal.

Shmuel's basic S'vara in the Reisha will not apply here by the division of the brothers - because here, the opposite is true, that brothers and partners prefer to divide the property as quickly as possible ...

... like the old saying goes - 'The pot belonging to partners does not get hot and does not get cold' (but remains lukewarm).