1) MAKING THE LENDER SWEAR THROUGH "GILGUL SHEVU'AH"
QUESTION: Rav Huna (34b) rules that whenever a Shomer does not return the Pikadon itself (and either claims that he is exempt or returns money in its place), he must swear that the object is not in his possession. Rav Huna bar Tachlifa in the name of Rava challenges Rav Huna's ruling from one of the cases mentioned in the Mishnah in Shevuos (43a). The Mishnah there presents several scenarios of a lender who lent a Sela to a borrower and received an item of collateral from the borrower, which he subsequently lost. The lender and borrower now dispute how much the item of collateral was worth. In one of the scenarios, the borrower claims that it was worth two Sela'im, and thus the lender owes him one Sela. The lender claims that it was worth one Sela, and thus he owes nothing. The Mishnah rules that the lender is exempt and does not even need to make a Shevu'ah (since he denies owing anything -- "Kofer ha'Kol"). The Gemara asks that if Rav Huna's ruling is correct, then the lender -- who was a Shomer for the collateral of the borrower -- must swear that the object is not in his possession. Accordingly, the principle of "Gilgul Shevu'ah" should also obligate him to swear as to the value of the collateral.
Why does the Gemara assume that the principle of "Gilgul Shevu'ah" would obligate the lender to make a Shevu'ah? In this situation, he should not become obligated to make a Shevu'ah because he has a "Migu": if he wanted to lie, he could have made a more effective claim and asserted that the borrower never gave him collateral in the first place. Although this "Migu" does not exempt him from the primary Shevu'ah that he must make (that the item is not in his possession), that is because it would be a "Migu d'He'azah" (that is, he would not have made the more effective claim because he would have had to be overly brazen to do so). With regard to the Shevu'ah about the value of the item, since the lender anyway denies that he owes the borrower any money, the claim of the "Migu" (that he never received collateral) would be on the same level of brazenness, and the "Migu" should therefore exempt him from the "Gilgul Shevu'ah." (REBBI AKIVA EIGER, CHASAM SOFER)
ANSWERS:
(a) REBBI AKIVA EIGER and the CHASAM SOFER answer that the "Migu" is still a "Migu d'He'azah" because the claim that he never received any collateral actually would require an extra degree of brazenness. Although the lender already denies owing anything (with his claim that the collateral was worth one Sela), this claim is not as brazen because the borrower will not assume that the lender is an outright liar; the borrower will assume that the lender simply made a mistaken assessment of the item's value. In contrast, if the lender claims that he never received collateral from the borrower, the borrower will accuse him of being a liar. Therefore, the lender would prefer not to make that claim, and thus he has no "Migu."
(b) CHIDUSHEI REBBI MEIR SIMCHAH answers that the "Migu" does not exempt him from the "Gilgul Shevu'ah" because the lender would not want to make the claim of the "Migu," that the borrower never gave him collateral. Since the object indeed may have been stolen from him, the lender will not claim that he never received it, because if he does he will not be able to retrieve the object from the Ganav. (I. Alsheich)

35b----------------------------------------35b

2) A "SHEVU'AH" TO APPEASE
QUESTION: The Mishnah states that when someone (a Socher) rents an animal from its owner and then lends it to someone else (a Sho'el) and it dies in the Sho'el's possession, the Sho'el must pay the value of the animal to the Socher, and the Socher must make a Shevu'ah that the animal died a normal death, and he is then not required to compensate the owner. In the Gemara, Abaye explains that the Socher receives payment from the Sho'el because he actually "acquires" the animal at the moment of its death. The Socher's obligation to make a Shevu'ah is merely "in order to appease the owner" so that he will not think that the Socher was negligent ("Poshe'a") in guarding his animal.
Why does the Gemara need to give a reason for this Shevu'ah? The Torah always requires a Shomer to make a Shevu'ah (a "Shevu'as ha'Shomrin") whenever he exempts himself from payment for a Pikadon. Why does the Gemara need to provide the additional reason for the Shevu'ah, "to appease the owner"? (Acharonim)
ANSWERS:
(a) REBBI AKIVA EIGER answers that the Shevu'ah that the Socher must make is not a Shevu'ah d'Oraisa. In general, the primary Shevu'ah of a Shomer, which is the Shevu'ah that the object is not in his possession, is a Shevu'ah d'Oraisa, and the other Shevu'os that a Shomer must make are all because of "Gilgul Shevu'ah." In the case of the Mishnah, the Socher is exempt from a Shevu'ah that the object is not in his possession, because the Sho'el himself makes a Shevu'ah (or brings witnesses to testify) that the animal died a normal death. Since the Socher has the right to lend out the animal, and since he does not have to make a Shevu'ah that the animal is not in his possession, mid'Oraisa he is exempt from any Shevu'ah. Hence, the only reason why he must make a Shevu'ah in this case is that he receives money from the Sho'el as compensation for the animal, and thus he profits from property that belongs to someone else (the animal's owner). The Chachamim therefore instituted that the Socher must make a Shevu'ah in order to appease the owner of the animal.
(b) The AVNEI KODESH answers that the Gemara adds this reason to explain why the Socher makes a Shevu'ah according to the view of Rami bar Chama. Rami bar Chama is of the opinion (Bava Kama 107a) that a Shomer does not make any Shevu'ah unless he is "Modeh b'Miktzas" and "Kofer b'Miktzas." (The Gemara there explains that the Shomer makes a Shevu'ah only if he was given three animals to watch and he returns one, claims to have lost another (Modeh b'Miktzas), and completely denies the third (Kofer b'Miktzas)). The Mishnah here, though, clearly discusses only one animal, and, consequently, there should be no Shevu'ah according to Rami bar Chama. Therefore, the Gemara explains that the reason for this Shevu'ah, according to Rami bar Chama, is a Takanah of the Chachamim in order to appease the owner.
(c) The OR SAME'ACH (Hilchos To'en v'Nit'an 1:12) explains that the "Shevu'as ha'Shomrin" actually is not like any other Shevu'ah d'Oraisa. The reason why the Torah itself requires the Shomer to swear is in order to appease the owner. Hence, the Gemara is explaining the reason why the Torah requires a Shomer to swear. (I. Alsheich)