The full Beraisa (cited earlier by Rav Nachman) citing Rebbi Yehudah, speaks about Reuven who pays Shimon five hundred Zuz out of his thousand Zuz debt. Rebbi Yehudah rules there that - the witnesses tear up the Sh'tar and write a new one backdated from the time of the original.

The two reasons Rebbi Yossi gives for writing a receipt are to force Reuven to pay the remainder of his debt quickly and - to enable Shimon to claim from the date on the original Sh'tar.

Rebbi Yossi found it necessary to add the second reason, in spite of the fact that Rebbi Yehudah agrees with him on this point is - because he was referring to Rebbi Yehudah in our Mishnah, where he is non-committal with regard to the date.

So when he gave the two reasons, what he really meant to say was that - if Rebbi Yehudah permits the witnesses to write the earlier date, then he only takes issue with him in the first point, but if he restricts them to writing the latter date (which is less radical), then he takes issue with him in that point, too.

Rebbi Yehudah in a Beraisa describes a Sh'tar that contains a date from the sun-year, which turns out to be a Shabbos or Yom Kipur - as a Sh'tar Me'uchar (post-dated), which is Kasher.

In any event, the Sh'tar cannot have been written on the given day - though it might alternatively be a Sh'tar Mukdam (pre-dated), in which case it would be Pasul (according to everybody).

It is clear from the Sugya in Makos that we consider the Sh'tar, Me'uchar rather than Mukdam. We can also prove it from 'Kiyum Sh'taros', which is only mi'de'Rabbanan - implying that min ha'Torah, a Sh'tar is Kasher anyway, because the onus lies on the defendant to prove the Sh'tar Pasul.

The basis for this ruling is a statement by Resh Lakish - who considers the signatures of witnesses on a Sh'tar as if they have been verified in Beis-Din.

Rebbi Yossi rules that a Sh'tar which contains a date from the sun-year is Pasul. When Rebbi Yehudah queried him from a similar Sh'tar which came before him in Tzipori, and which he declared Kasher he replied that - that case referred to the same case as Rebbi Yehudah was talking about.

Rebbi P'das therefore establishes their Machlokes - by a regular Sh'tar Me'uchar (where there is no indication in the Sh'tar itself that it was not written on the day that the loan took place).

Rebbi Yossi differentiates between the two kinds of Sh'tar, declaring ...

... the latter Pasul - because we are afraid that, in a case where the debtor paid half his debt, and the creditor wrote him a receipt dated on the day that he paid him, the creditor will eventually produce the same Sh'tar again, which, because it is post-dated (to a date later than that of the debtor's payment) will enable him to claim that it is a new debt that took place after the first repayment.

... the former Kasher - because, the fact that the date clearly indicates that the original Sh'tar was Me'uchar, will make if impossible for him to claim with it again.

Rebbi Yossi will issue the same ruling in the equivalent case, where the debtor (did not pay half his debt, but where he) the creditor lost his Sh'tar ...

... since there too, we are afraid that the creditor will find the Sh'tar, and use it to claim again, as we just explained.

Rebbi Yehudah - validates a Sh'tar Me'uchar in all of the above cases, since he holds 'Ein Kosvin Shover', and there is nothing to be afraid of.

Rav Huna b'rei de'Rav Yehoshua tries to restrict Rebbi Yossi's ruling ('Kosvin Shover') to where the debtor paid half - and where the current dilemma is not the creditor's fault. But in a case where he lost his Sh'tar - which is negligence on his part, he thinks that Rebbi Yossi will concede to Rebbi Yehudah that 'Ein Kosvin Shover'.

And we prove this from a second episode where Rav Yitzchak bar Yosef lent Rebbi Aba money. When the former claimed to have lost the Sh'tar, and volunteered to write a receipt, the latter quoted Rav and Shmuel, who hold - 'Ein Kosvin Shover.

When Rav Yitzchak bar Yosef countered Rav Yitzchak bar Yosef, his opening words were 'Ma'an Yahiv lan me'Afra de'Rav u'Shmuel Raminan be'Aynin', by which he meant that - he revered Rav and Shmuel to the extent that he wished they would throw some of the dust from their graves in his eyes.

Nevertheless, he argued - Rebbi Yochanan and Resh Lakish (like whom we rule against Rav and Shmuel) hold 'Kosvin Shover'.

Ravin Amar Rebbi Ila'a too holds 'Kosvin Shover'. And we conclude the Sugya with the argument and counter argument, why each one should not have to look after the Sh'tar. Rava's final word is that - logically, we have to rule 'Kosvin Shover', because of the principle 'Eved Loveh le'Ish Malveh' (as we explained Rebbi Yossi earlier). Consequently, the Loveh will have to accept the fact that he has to look after the Sh'tar.

We learned in the Mishnah in Shevi'is 'Sh'tarei-Chov ha'Mukdamin Pesulin, ve'ha'Me'ucharin Kesheirin'. The Reisha speaks about a case where the creditor pre-dated the Sh'tar. A Sh'tar Mukdam which is written on the current date, only the loan did not take place until later, is subject to a Machlokes Amora'im in Bava Metzi'a.

Abaye considers such a Sh'tar Mukdam Kasher -because he holds 'Eidav ba'Chasumav Zachin lo' (from the moment the borrower wrote the Sh'tar, he is Meshabed his property to the creditor, and the signatures validate the Shibud immediately), in which case it is not a Sh'tar Mukdam at all).

Rav Hamnuna confines this to a Sh'tar-Chov; a Sh'tar Mekach u'Memkar Me'uchar is Pasul - because we are afraid that the seller will obtain money in the interim and redeem the property that he sold in Nisan but which was dated in Tishri. The purchaser, claiming that he lost his Sh'tar, will give the seller a receipt that he redeemed it in Tamuz (even according to Rebbi Yehudah, since there is nothing to lose). Then when the date on the Sh'tar arrives, he will produce the Sh'tar and claim that he bought the field a second time after having sold it back to the owner.

A Sh'tar-Chov Me'uchar is not Pasul for the same reason - because the author of the Mishnah in Shevi'is is Rebbi Yehudah, who holds 'Ein Kosvin Shover'.

Later, it became customary to write Sh'tarei-Chov Me'ucharin, even though they would write a Shover. Rav Yeimar (or Yirmiyah mi'Difti) attributes this to a statement by Rebbi Aba, who instructed his Sofer to write in the Sh'tarei-Chov Me'ucharin that - it was a Sh'tar Me'uchar (and as we learned earlier, whenever the suspicious aspect of the date is marked explicitly in the Sh'tar, there is nothing to fear).

Rav Ashi reconciled a later Minhag still, to write a receipt, with the fact that they would nevertheless validate a Sh'tar Me'uchar, even without concurring with Rebbi Aba, by citing Rav Safra who instructed his Sofer to insert the date of the Sh'tar Me'uchar in the receipt - and if they did not know it, to omit the date altogether (thereby removing any reason to invalidate the Sh'tar).

The creditor is therefore advised - not to make any loans to the debtor as long as he has that receipt in his possession, because the receipt will negate any Sh'tar that the creditor produces.

When Ravina asked Rav Ashi (or Rav Ashi to Rav Kahana) why even that advice was not being adhered to he replied that - Chazal cannot do more than issue decrees, and those who fail to adhere to them must suffer the consequences.