When Ravina, whose four fields surrounded his field on all four sides, and who had built a partition Mechitzah on all four sides, asked him for ...

... half the costs of the Mechitzah - he ignored the request.

... half the cost of a fence of cheap canes - he still ignored it.

Ravina then asked him - to pay half the costs of a guard to keep the goats out.

When Ravina once spotted him picking dates from his date-palm, he set out to prove that Runya was benefiting from the Mechitzahs - by instructing his Aris to help himself to a bunch of dates, in Runya's presence. When Runya shouted at him to stop, it was clear that the dates were precious to him, and that he was therefore benefiting from the Mechitzah.

When, in response to the above episode, Runya argued that one does not need a Mechitzah to protect one's date-palms from the goats, because shouting at them is sufficient, Ravina replied that this too, would entail hiring a guard (and that he should therefore pay him at least, for half the costs of a guard, as he had already requested).

When the case came before Rava, he ruled - that unless Runya appeased Ravina (to pay at least for the guard), he would make him pay for a Mechitzah, like Rav Huna according to Rebbi Yossi ...

... like whom Rava clearly rules.

When Runya purchased a field next to Ravina's, Ravina applying the principle Diyna de'bar Metzra, claimed it, but Rav Safra brei de'Rav Yeiva said 'Arba le'Tzala, Arba'ah le'Tzelala' - by which he meant that Ravina should be so good as to leave the field for Runya (See Tosfos DH 'Arba'ah').

One explanation is that 'Tzala' means a poor leather-maker, and 'Tzalela', a rich one, and, since each one requires four loaves to feed his family per day, Ravina should leave the field for Runya, who needed it for his Parnasah more than he did (see Rabeinu Gershom). We reject this explanation however - on the grounds that 'Tzala' means leather, and not a leather-maker.

Based on the fact that Runya was a leather-maker, it means - that Ravina should leave the field for Runya, who, as a leather-maker, earned very little, as the old saying went 'Four Zuzim to purchase the skin and four Zuzim to pay the tanner' (leaving the leather-maker little room for profit).

Our Mishnah rules that if a Mechitzah (six Amos high, for example) dividing between two Chatzeros, collapses - both parties are obligated to build a Mechitzah up to a height of four Amos.

If, after rebuilding the Mechitzah, Reuven claims half the expenses, and Shimon counter-claims that he has already paid - he is believed, because we are witnesses ('Anan Sahadi') that Reuven would not have built the entire Mechitzah out of his own pocket without claiming half the expenses from Shimon.

If however, Reuven rebuilt the Mechitzah of six Amos, and, after refusing to share the costs, Shimon builds a Mechitzah of six Amos adjacent to it - he is obligated to share the full cost of Reuven's Mechitzah.

If, in this latter case, Reuven claims half the expenses of the six-Amah Mechitzah, and Shimon counters that he has already paid - he is not believed, because, since this is not a straightforward case, 'Anan Sahadi' that he would not have paid before Beis-Din obligated him to do so.

According to Reish Lakish, if Reuven lends Shimon money to be paid by a given date, and Shimon claims that he paid before the expiry-date, he is not believed. Abaye and Rava say - he is ...

... because sometimes he happens to have money available, so he goes and pays..

We try to support Abaye and Rava from the Reisha of our Mishnah 'be'Chezkas she'Nasan ad she'Yavi Re'ayah she'Lo Nasan'. In our case, the equivalent of 'after the expiry date' and 'before the expiry date' respectively is - after 'Reuven has finished building his Mechitzah' and before he has finished building it'.

We now try to support Abaye and Rava from the Reisha of our Mishnah 'be'Chezkas she'Nasan ad she'Yavi Re'ayah she'Lo Nasan' - from the fact that this must be speaking 'during the time' (Toch Zemano), because if the Tana was speaking 'after the time', then what would be the Chidush?

We refute it however, in that - here is different, because as each row is completed it is considered its time), in which case there is no 'Toch Zemano'.

We learned in the Seifa of our Mishnah (in the case where Shimon built a Mechitzah parallel to Shimon's six-Amah Mechitzah) 'be'Chezkas she'Lo Nasan ad she'Yavi Re'ayah she'Nasan'. On the assumption that the Tana must be speaking where Shimon claimed to have paid before the time, we try to prove - that 'Ein Adam Pore'a be'Toch Zemano' (like Reish Lakish).

Initially, we think that the Tana cannot be speaking where Shimon claimed that he paid before the time - because then there would be no reason for him not to be believed.

We refute that assumption however - like we already explained in our Mishnah, by pointing out that even if Shimon claims that he paid after the time, he will not be believed, because, seeing as this is not a clear-cut ruling, Anan Sahadi that he would not have paid before Beis-Din obligated him to do so

Rav Papa and Rav Huna b'rei de'Rav Yehoshua rule like Abaye and Rava ('Adam Pore'a Toch Zemano'); Mar bar Rav Ashi rules like Reish Lakish ('Ein Adam Pore'a Toch Zemano'). The Halachah is - like Mar bar Rav Ashi.

We conclude the previous ruling with 'va'Afilu mi'Yasmi' - which means that if Shimon dies, after claiming that he paid his debt Toch Z'mano, Reuven may even claim from his Yesomim.

The significance of this statement is - that Reuven does not even need to swear to substantiate his claim (even though under normal circumstances, one cannot claim from Yesomim without a Shevu'ah).

We ask whether Shimon will be believed, if he claimed after the expiry-date that he paid already before. In spite of having just concluded 'Ein Adam Pore'a Toch Zemano', he might nevertheless be believed - because he has a 'Migu' (he could have claimed to have paid after the time, in which case he would have been believed.

'Mah lo Le'shaker' means - 'Why would a person lie, when he can obtain the same results by telling the truth'.