Rebbi Aba bar Mamal Amar Rav cites the Rabanan, who disagree with ben Nanas in our Mishnah. In a case where Reuven said 'Midah be'Chevel Ani Mocher lach Hein Chaser Hein Yeser' or vice-versa - they consider it a Safek whether we follow the first Lashon or the last. Consequently, they rule 'Cholkin' (or go after whoever is Muchzak like Shmuel later).

In the Mishnah in Bava Metzia, in a case in Tzipori, where Shimon rented a bathhouse from Reuven in Tzipori at twelve golden Dinarim for a year, a golden Dinar a month, and it turned out to be a leap-year, Raban Shimon ben Gamliel and Rebbi Yosi rule that - Reuven and Shimon share the extra month .

Were it not for Rebbi Aba bar Mamal Amar Rav - we would have attributed Rabban Shimon ben Gamliel and Rebbi Yossi's doubt to the fact that, on the one hand, Shimon might have changed his mind when he added 'at a golden Dinar a month', whereas on the other, he might have merely been explaining his initial stipulation of 'a Dinar a month', a S'vara with which ben Nanas may well agree. But in our Mishnah, where the two Leshonos definitely contradict each other, they will concede that 'Tofeis Lashon Acharon'.

According to Rebbi Aba bar Mamal, the Rabbanan's ruling both in our Mishnah and in the Mishnah in Bava Metzia - is based on the principle 'ha'Motzi me'Chavero alav he'Re'ayah'.

According to our initial assumption, that the Tana'im of 'Merchatz' hold 'Pirushi ka'Mefaresh', the ramifications of 'Dinar Zahav la'Chodesh', besides the fact that Reuven will receive the extra Dinar are that - Reuven gets paid at the end of each month (and not at the end of the year, as is customary in the realm of Sechirus), and that he therefore has the right to terminate the contract at the end of each month.

The basis of the Rabbanan's Safek (as well as ben Nanas' ruling 'Tofeis Lashon Acharon') is the fact that the two statements were made within 'Toch K'dei Dibur' (the time it takes to say 'Shalom aleichem Mori' or 'Mori ve'Rebbi').

Rav Yehudah Amar Shmuel too, holds that the Chachamim disagree with ben Nanas; only he quotes them as saying 'Halach achar Pachos shebe'Leshonos' meaning that the purchaser receives the lesser of the two amounts ...

... because they are not sure whether we adopt the first Lashon or the last.

The ramifications of this ruling regarding 'Midah be'Chevel ani Mocher lach hein Chaser hein Yeser' are that - if it transpires that Reuven gave Shimon more than a Beis-Kur, he may reclaim the balance (Midah be'Chevel); whereas if he gave him less, Shimon has to accept it (Hein Chaser hein Yeser).

Rav and Shmuel both rule in a case where Reuven said to Shimon ...

... 'Kur bi'Sheloshim ani Mocher lach' that - they can retract right up to the last Se'ah (even if Shimon made a Meshichah on each Se'ah before pouring it into his container).

... 'Kur bi'Sheloshim ani Mocher lach, Se'ah be'Sela' that - Shimon acquires each Se'ah as he pours it into his container.

We currently ascribe Shmuel's latter ruling to the principle T'fos Lashon Acharon', like ben Nanas in our Mishnah. Even though Shmuel's earlier statement 'Zu Divrei ben Nanas, Aval Chachamim Omrim ... ' implies that he does not hold like ben Nanas - we are now forced to say that 'Zu' u'Sevira leih' ('These are the words of ben Nanas' and that is how he holds).

In the case of the bathhouse, Shmuel rules that if Reuven and Shimon arrived in Beis-Din ...

... at the beginning of the thirteenth month - the owner may ask the hirer to leave or to pay him for the coming month.

... at the end of the thirteenth month - he is not obligated to pay for that month ...

... whereas Raban Shimon ben Gamliel and Rebbi Yossi ruled 'Yachloku es Chodesh ha'Ibur' in a case where Reuven and Shimon came to Beis-Din in the middle of the month.

Shmuel's reason for this ruling is - because he holds like the Chachamim of ben Nanas, who are uncertain whether we adopt the first or the last Lashon, so whoever is Muchzak gets to keep what he has (not like Rav's interpretation of their ruling).

And he rules in the case of 'Kur bi'Sheloshim Se'ah be'Sela, Rishon Rishon Kanah' - for the same reason, because until Shimon acquires the grain, Reuven is Muchzak, but the moment he pours it into the Shimon's vessels, he (Shimon) becomes Muchzak.

If Reuven inverts the order and says 'Se'ah be'Sela Kur bi'Sheloshim ani Mocher lach' - Shmuel will still hold 'Rishon Rishon Kanah' ...

... whereas according to Rav, who holds like ben Nanas ('T'fos Lashon Acharon'), Shimon will not acquire the grain until all thirty Se'ah have been poured into his vessel.

Rav Huna quoting Amri bei Rav - Rav Hamnuna, rules that 'Astira Me'ah Ma'i, Me'ah Ma'i; Me'ah Ma'i Astira, Astira'.

An Astira is half a Sela Medinah (alias half a Dinar [an eighth of a Sela Tzuri]), which is the equivalent of ninety-six P'rutos (1 Dinar = 6 Ma'ah, 1 Ma'ah = 2 Pundiyon, 1. Pundiyon = 2 Isrim, 1 Isar = 8 Perutos); whereas ...

... 'Me'ah Mai' is equivalent to a hundred P'rutos.

Amri bei Rav is now coming to teach us - 'T'fos Lashon Acharon' (like ben Nanas).

Rav stated that had he been in Tzipori when the episode of the bathhouse took place ('bi'Sheneim-Asar Zehuvim le'Shanah, Dinar Zahav le'Chodesh'), he would have sided with the owner of the bathhouse - because, as we just explained, he holds like ben Nanas.

In spite of Rav's latter ruling, Amri bei Rav (who was a Talmid of Rav) found it necessary to issue the former statement (in the case of the bathhouse) - because otherwise, we might have ascribed his ruling there to the fact that the second stipulation ('Dinar le'Chodesh') comes to explain the first ('Sheneim-Asar Zehuvim le'Shanah'), and not to contradict it (as we already suggested on the previous Amud).

Had we indeed learned like that, Rav would have then held in the case of 'Astira Me'ah Ma'i ... ' that we go after the Muchzak, like Shmuel (or 'Yachloku', like we learned at the beginning of the Sugya).

Clearly the last of Rav's above rulings was - that of 'Astira Me'ah Ma'i', which comes to teach us categorically that Rav holds like ben Nanas, as we explained.

We refute the text in Bava Metzia (with reference to the case of 'Astira Me'ah Ma'i ... '), 'I me'Hasam, Havah Amina Pirushi ka'Mefaresh', meaning that 'Astira' refers to a large Sela worth a hundred P'rutos (and in the reverse case, that 'Me'ah Ma'i' refers to a hundred small ones either because then Rav might just as well have switched 'Astira' for ninety-six Perutos (which are not subject to interpretation) or - because, if anything, it is the case of the bathhouse (with which the Sugya there is contrasting 'Astira Me'ah Ma'i') which is subject to interpretation, as we explained (and not 'Astira Me'ah Ma'i').

In the case of the bathhouse, we rule neither like Rav ('T'fos Lashon Acharon') nor like Shmuel ('be'Ba be'Emtza ha'Chodesh Askinan'), but like Rav Nachman in Bava Metzia - who sides with the owner in all cases, because of the principle 'Karka be'Chezkas Ba'alehah' (land is always in the owner's possession, so he is considered Muchzak, even if they only arrived in Beis-Din at the end of the month).