Observation: In Sanhedrin (6b), the Gemara derives this from the Pasuk, "Lo Saguru" -- "do not be afraid." This is the way of the Shas in many places (to quote different Pesukim as sources for a law).

Question: Why is he more scared about a Gilgul Shevuah than the current Shevuah that he must take because of this claim?

Answer: The case is where he does not have enough money to pay for all of the money that he would owe through the Gilul Shevuah. For example, he could owe him a lot of money for other reasons. He will therefore think that he will deny this too, and stall until I have money to pay off all of my debts to him, at which time I will pay him in full.

Observation: In Sanhedrin (7b), the Gemara derives this from the Pasuk, "Shamoa Bein Acheichem" -- "listen amongst your brothers."

Explanation: This is referring to someone who does this because he is a tough person who knows how to make claims, and is fighting someone else's fight. However, when he takes out time to get his friend his money when his friend cannot do so, he is doing a Mitzvah.

Implied Question: This is despite the fact that the Gemara later (32b) says that everyone agrees regarding a witness who knows that a woman's husband is dead that he is liable. This is because the Rabbanan said he is fit to testify in this case, and we deem the Rabbanan as the standard. (How, then, can our Gemara say that he is liable because the Torah says he is a valid witness?)

Answer: We use both standards to make him liable to bring a Korban. Being that his testimony is helpful mid'Rabbanan in the Gemara later (32b), there is a monetary loss caused by him not testifying. In our Gemara, even though his testimony does not help mid'Rabbanan, being that it helps according to Torah law, he is liable.

Implied Question: The Rabbanan did not want to derive this from a deposit. (Why not?)

Answer: If they derive this from a deposit using a Meh Matzinu, it would be possible to ask that an oath regarding a deposit applies to both men and women (unlike Shevuas Ha'Eidus).

Answer(cont.): Rebbi Meir derives this from a Gezeirah Shaveh of "Secheta-Secheta," as does Rebbi Shimon later (34a).

Explanation: This means that one can prove from the Mishnah regarding Shevuos ha'Pikadon that the Rabbanan hold of Don Minah v'Uki b'Asra. However, we cannot prove that Rebbi Meir holds Don Minah u'Minah from that Mishnah. We can only prove that from our Mishnah.

Explanation(cont.): We can explain that Rebbi Meir's reasoning regarding the Mishnah there is because he learns Shevuas ha'Pikadon as a Kal v'Chomer from Shevuas ha'Eidus. A Shevuos ha'Eidus is not taken by women, and one is liable whether he took the oath on his own or it was administered from others. Certainly the same should apply to Pikadon. However, one can only derive with a Kal v'Chomer as much as applies to the source of the Kal v'Chomer. Accordingly, just as a Shevuas ha'Eidus can only be administered by others in Beis Din, so too this is true regarding a Shevuas ha'Pikadon.

Implied Question: One cannot say that a Shevuas Bituy should prove that this is incorrect. This would be because a Shevuas Bituy is the same regarding women and men, and one who is sworn by others is exempt. (Why not?)

Answer: This is because the status of a person who makes a Shevuas Bituy on purpose and accidentally is different, as the Pasuk says "And it was hidden."

Answer(cont.): If there would be no question, I would think that a Shevuas Bituy itself should be derived from Shevuas ha'Eidus in order to make one who takes an oath from others liable.

Opinion#1: Rashi explains in the beginning of the chapter that the case is where he forgot the testimony.

Question: Why don't we simply say that he swore truthfully? (At the time, he truthfully did not know any testimony about this matter!)

Answer: The case is where they swore, "Shevuah that we do not know and/or have never seen any events regarding this case."

Question: Even so, how does this have to do with the case of Rav Kahana and Rav Asi? Perhaps here the reason is because they are not fit to testify, and they are therefore like relatives or people who are invalid witnesses?

Answer: They are not like invalid witnesses, as regarding them (Rav Kahana and Rav Asi) the Pasuk, "And he is a witness," does not apply, as Rashi explained in the beginning of the chapter that one has to be fit to be a witness (for a Shevuas ha'Eidus to apply). However, here the Pasuk "And he is a witness" does apply (to both these witnesses and the case of Rav Kahana and Rav Asi), as they are fit to be witnesses if they would remember what happened in an accurate manner.

Opinion#2: Additionally, it is possible to say that the Gemara means that they think it is permitted to swear falsely.

Explanation#1: This is according to Rebbi Meir, who holds that one is liable outside of Beis Din if he swears on his own. This is why the Mishnah has to say that they say Amen, as this is like he is swearing himself.

Explanation(cont.): The Tana is stating all types of cases of swearing on his own. If this would be according to the Rabbanan and is taking place in Beis Din, why do they have to say Amen to be like someone who swore on his own? We should derive that even if the oath was administered by others he should be liable!

Explanation#2: Alternatively, this is even according to the Rabbanan. The Mishnah says, "And they say Amen" in order to shorten the case. The same law would apply if they said afterwards, "We do not know any testimony in your case."

Explanation(cont.): The second part of the Mishnah that says, "He made him swear five times outside of Beis Din etc." is also like the Rabbanan. The Rabbanan also do not require a Shevuah in Beis Din. They only require a denial in Beis Din. The Torah was only stringent that the people state they do not know testimony in Beis Din, in a place that "is fit for telling."

Explanation(cont.): This is now understandable. The Gemara implies that the derivation from, "for one" that makes one liable for every such Shevuah is indeed a required derivation, even according to the Rabbanan.