Explanation: If he already swore, [the other party] cannot retract. However, if he did not swear, [the other party] can retract, like we say in Sanhedrin (24b);

Citation (24b): The argument is after the final verdict, but before the final verdict, all agree that he can retract.

Here, even though he said "swear and receive", since he did not swear yet, this is before the final verdict.

Support: It connotes like this in Bava Metzi'a (34b). If [a deposit was stolen, and the Shomer] said "I will pay", and retracted and said "I will not pay", what is the law? (If the thief was found, who receives the Kefel?) Do we say that he retracted (so he does not receive Kefel? Or, he still intends to pay, just not now?)

Inference: He can retract, for this is like before the final verdict.

Implied question: It says in Shevuos (39a) that if one said "I will not swear", we exempt him immediately. (His opponent is exempt, for he cannot retract and swear!)

Answer #1 (R. Tam): It means that we remove [the one who said so], so he will be embarrassed to retract, but if he wants to return to Beis Din and swear, he may.

Question: What is [the Gemara's] source for what it says here that [R. Aba] holds that the Halachah follows Chachamim? Perhaps he holds that they argue about before the final verdict, but after the final verdict, all agree that he cannot retract!

Answer #2 (Rashi): If he said "I will not swear", we exempt [his opponent] immediately, for he cannot retract;

Here the text says "Nishba" without a Vov. He swears Bal Korcho. (I.e. if Reuven said "swear and collect", and now wants to retract, he cannot. His opponent swears and collects against Reuven's will.)

Implied question: In Bava Metzi'a (34b), it says "do we say that he retracted?" (This implies that he can retract!)

Answer: Even though he cannot retract, still, since he wanted to retract, and toil the owner to come to Beis Din (to try to force the Shomer to pay, the owner) is not Makneh the Kefel to him. It says like this there.

Question: This Perush is difficult. In our Sugya, we rule like all the teachings that R. Aba sent. If so, even before the final verdict he cannot retract. In Sanhedrin (24b), we concluded that before the final verdict he can retract!

Answer: Perhaps here, even before the Shevu'ah, it is considered a final verdict once he said "if you want, swear and receive."

Question: Even a Sheni with a Sheni (sons of brothers), it says in Sanhedrin (28a) that they are Pasul [for testimony], and all the more so a grandfather!

Answer: We can say that a grandfather is more Kosher, for he is distanced another generation.

Explanation #1 (Rashi): One is Pasul [to his descendants] for all generations.

Rebuttal (and Explanation #2 - Ri): [He is Kosher,] since he is distanced so many (at least three) generations.

Implied question: Regarding a Get [that a Shali'ach brought from Chutz la'Aretz; the Shali'ach must validate it], we are Machshir! If he could see at the time it was written, he may say "it was written and signed in front of me" after he became blind!

Answer: There is different, for Rabanan were lenient to be Machshir even a woman and relatives.

Explanation (Ri): He is believed through a Shevu'ah because it is considered like a Milveh Al Peh (a loan without a document), for the witnesses testify that the document was paid.

Implied question: According to him, the witnesses are Pesulim, for he contradicts them, and says that he owes half!

Answer: In any case the document is validated only through his admission, and he says that he paid half.

Implied question: This should be like [a borrower] who admits that he wrote (authorized) a document. He is not believed to say "I paid", and [the lender] collects from Meshubadim, even though it is validated only through [the borrower]!

Answer: There, it is a proper document, and witnesses who signed on a document, it is as if their testimony was investigated [and accepted] in Beis Din, just Rabanan required Kiyum (validation) when [the borrower] explicitly claims that it was forged;

However, when [the borrower] validated it, it is a proper document, and he is not believed to say "I paid."

Assertion (Ri of Orlins): The text does not say "R. Akiva", rather, "R. Yakov." It is not proper to elaborate more. (Chidushei ha'Ran (Bava Metzi'a 4b DH Iy) - some change the text because R. Akiva expounds Ribuy u'Mi'ut. If so, he holds that we do not swear about documents.)

Question (Ri): Why does it attribute the reason "because he fears" to the existence of witnesses, that he fears lest they contradict him?

Even if merely they do not help him, he cannot deny everything and be brazen, for one cannot be brazen to his creditor to deny everything (Bava Metzi'a 3a)!

Answer: Since he thinks that witnesses will come to support him, for he brings them and they told him their intent, there is no [obstacle of] brazenness if he will deny everything;

If he did not fear lest they retract and contradict him, he would have a good Migo. However, because he fears lest they contradict him, he is not pleased to deny everything, lest he appear to be more of a liar if they contradict him.

Question: We hold that Heilach (one who partially denies a claim, and immediately pays the amount he admits to) is exempt, like R. Chiya (Bava Metzi'a 4a), and here we rule that [the lender] swears and collects half;

This document, since he admits to it, is Heilach! (It is as if he already collected it.)

Answer: A document is considered Heilach only if one can collect Meshubadim through it.