Answer#1: It is possible to answer that Rava holds like the opinion that one does not need to clarify his claim (as long as it is a winning claim).

Answer#2: Alternatively, as Rabeinu Tam explained, one must verify the truthfulness of his words as much as he can. Even so, if he cannot find the witnesses or they came and deny this ever happened, he does not lose.

Answer#2(cont.): This is also apparent from the Yerushalmi that Rabeinu Chananel quotes. The text in the Yerushalmi is that if someone claims he has a document of ownership and that he has a Chazakah, Rebbi says he is judged by the document, meaning that he must prove this claim. Rabban Shimon ben Gamliel says, he must prove the Chazakah. An incident occurred before Rebbi, and he ruled according to Rabban Shimon ben Gamliel. The Yerushalmi asks, this is a contradiction! The Yerushalmi answers that Rebbi only wanted to clarify what had happened.

Text: Some have the text there that the incident came before Rebbi Chiya, and that the Gemara asks a question from that incident on Rebbi, as Rebbi Chiya was Rebbi's student (and therefore presumably held like him). This is similar to the question in Shabbos (128a) from Rav Huna on Rav, because Rav Huna was Rav's student.

Opinion: Rashi explains in Sanhedrin (23b) that according to the opinion that one must clarify his claim, if he seeks to do so but fails, he loses.

Opinion#1: Rabeinu Chananel and Rabeinu Tam explain that (practically) this means that the owner of the document must swear he was not paid.

Implied Question: The Gemara in Kesuvos (36b) says that one does not collect with a weakened document. (How can Rabeinu Tam say he can collect with an oath?)

Answer: The Gemara there is referring to a specific type of weakened document. Being that the claimant there already tried to hire witnesses to forge a document, it is understandable to say that he forged the document that he presented to Beis Din and forged the signatures.

Question: There is a difficulty from the Gemara in Kesuvos (85a). A document was presented to Rava. Rav Papa said to him that I know that this document has been paid. Rava asked him, "Is there anyone else who supports your claim etc.?" [Rava did not believe Rav Papa alone. However, in a similar circumstance, Rava believed his wife (the daughter of Rav Chisda) that a document had been paid.] The Gemara concludes that Rav Papa should not be worse than the daughter of Rav Chisda.

Question(cont.): What could Rava have done more than making him swear? He cannot tear up the document, as the Gemara there asks, "Do you think he tore up the document?!" Anyone who a judge does not know (his nature) well is still believed to make the claimant swear, as one witness is testifying that the document is paid! (In other words, what practical difference occurred due to Rava's wife's statement that did not occur when Rav Papa stated the document was paid?)

Opinion#2: It therefore appears that a weakened document is not torn or collected from, as stated in the case in Kesuvos (36b).

Explanation: This means he is not exempt with a Migu.

Observation: Everything is explained in Kesvuos (18 DH U'VIKULEI) and in Gitin (51b).

Explanation#1: It is possible to steal land as well, as in a case of someone who moves over the border between his property and that of his friend.

Explanation#2: Alternatively, the case is where there are grapevines loaded with grapes, and the guardian claims that they were stolen. Rebbi Meir would also agree (this is land) in a case where they are not ready to be harvested.

Explanation: This is only stated in the Mishnah because of things dedicated to Hekdesh. It does not have to be stated regarding land and servants, as it only applies to an ox and sheep, as stated in Bava Kama (62b).

Explanation: Being that the Pasuk is discussing a Shomer Chinam when it mentions taking an oath, the Mishnah says he does not take an oath. However, he also does not pay if he is negligent (with the items mentioned in our Mishnah), just as a Shomer Sachar is exempt from his liability of (these items) being stolen or lost.

Opinion: It appears that a Shomer Sachar would also be exempt from negligence.

Proof: This is as stated in Bava Kama (93a) regarding Tzedakah money that came to Pumbedisa. Rav Yosef deposited it by a person, who was then negligent with the money, which ended up being stolen by thieves. Abaye wanted to say the guardian is exempt, as the Pasuk says (regarding a guardian who is liable), "to guard" implying that the purpose of the deposit is to guard it, not to be distributed to the poor.

Proof(cont.): In that case, the guardian was a Shomer Sachar for Rav Yosef. This is as the Gemara says later that a person watching a lost object is like a Shomer Sachar because he does not have to give bread to a poor person (when he is watching the object).

Implied Question: The Mishnah also could have said that a Shomer Sachar does not swear that he is a victim of forced circumstances.

Answer: Rather, the Mishnah is discussing the first oath mentioned in the Pasuk. Being that it says that a Shomer Chinam does not swear, meaning he does not swear regarding his claim that the item was stolen, it also says that a Shomer Sachar does not pay for theft. (However, it is not discussing cases of forced circumstances.)

Implied Question: It also could have said that a borrower does not pay if he was a victim of forced circumstances or even if it the item was stolen, as he is compared to a Shomer Sachar in this regard. Accordingly, if he borrowed a house and it was burned down, he would be exempt. (The answer above answers this question as well.)

Answer: Additionally, the Mishnah did not state this case (of borrowing) because one cannot lend Hekdesh.

Implied Question: This is despite the fact that the Mishnah did state the payment of four or five times regarding oxen and sheep (even though it is only relative to Hekdesh (see Tosfos DH "v'Lo" above) and one is not allowed to do so).

Answer: This is because all of the things listed can be sold (even though they will not mandate a payment of four to five times the amount). However, the Pasuk excluded even other movable objects from being included in the penalty of four to five times the amount (certainly land and servants are excluded).

Question: This is difficult. It is understandable according to the opinion in Bava Kama (63b) that one Pasuk refers to a thief who stole the deposit, and the other is discussing the Shomer who is claiming it was stolen. The Pasuk is needed to exclude the thief himself from paying Keifel. However, according to the opinion that they are both regarding a case where the Shomer claims the item was stolen, there is no reason to have our Gemara's exclusion from Keifel, being that he is excluded from taking an oath altogether! (In other words, it is obvious he would never pay Keifel without the derivation from the Pasuk mentioned in our Gemara.)

Question(cont.): This is because it is not possible to collect Keifel from the Shomer when he claims the item was stolen unless he swears (falsely before he is discovered to have stolen the object), as is stated in Bava Kama (ibid.). One cannot say that the case is where the Shomer jumped up and swore, as in Bava Kama (106a) the Gemara implies that he would not pay Keifel unless he swore in Beis Din.

Answer: It is needed in a case where he is required to take this Shevuah through Gilgul Shevuah. (Gilgul Shevuah means that a person must take an oath he would normally not be obligated to take once there is a different related oath he is obligated to take.)

Question: However, this is difficult. Why do we require the Pasuk "his friend" to exclude Hekdesh from Keifel? Gilgul does not apply to Hekdesh!

Answer: In the conclusion of the Gemara in Bava Kama (ibid,) there is only one "Klal, u'Perat, u'Klal" regarding Shevuah and Keifel, and both of these are excluded from the Pasuk, "On every criminal act," as is implied in Bava Kama (ibid.). The Pasuk is discussing the entire topic. It says, if "on every criminal act" is used for a Klal u'Perat, it should say these exclusions regarding these etc. Just as the derivation of "When he will give" is referring to the entire topic, so too "On every criminal act" is referring to everything.

Implied Question: You might say that there is no need to specify "money or vessels."

Answer: We derive earlier that just as vessels is a minimum of two etc. (see 39b).

Question: Even so, why do we require "his friend" to exclude Hekdesh? We should derive this from the Pasuk, "And it will be stolen from the house of the person." This is as we derive in Bava Kama (76a), "and not from the house of Hekdesh."

Answer#1: It is possible to answer that this derivation actually relies on the words "his friend." The main aspect of the verse is to teach, "And it will stolen from the house of the man" and not from the house of the thief. This is also stated regarding Hekdesh.

Answer#2: Alternatively, that Pasuk is referring to the thief himself. In our Gemara, we require this for a Shomer who claims the object was stolen.

Observation: According to the conclusion of the Gemara in Bava Kama (ibid.), the Pasuk is not derived through Klal u'Perat. The Gemara concludes that "on every criminal intent" is a Ribuy (inclusive). One of these exclusions excludes land, and one excludes servants etc. The Tana here said, "Klal u'Perat u'Klal" because he was talking quickly, as the things mentioned in our Gemara can also be excluded using Klal u'Perat u'Klal.