GEMARA

One cannot reverse an oath mid'Oraisa (refuse to swear, and require the claimant swear to collect). One can reverse an oath mid'Rabanan.

Mar bar Rav Ashi holds that he can reverse even a Torah oath.

R. Yosi holds that if the defendant is Pasul (disqualified from swearing), we reverse a Torah oath onto the claimant, and he pays. Mid'Rabanan oaths are enactments. We do not enact (to reverse the oath) for an enactment.

Bava Basra 49b (Rava): If an enactment was made to benefit a person, he can say 'I do not want the enactment.'

Shevuos 46b (Rava): R. Yehudah says that when the Torah obligates the employer to swear, Chachamim enacted that the worker swears and collects. If he must swear only mid'Rabanan, there is no second enactment for the worker. Chachamim say that in both cases the worker swears and collects.

Kesuvos 87b (Mishnah): If one witness says that the Kesuvah was paid (she must swear to collect).

(Rava): The oath is mid'Rabanan, to appease the husband.

(Rav Papa): A clever husband will force her to swear mid'Oraisa. He pays the Kesuvah again in front of a second witness. He joins the witnesses and claims that the first payment was a loan. (She contradicts the first witness.)

RISHONIM

Rif (20a): For a Torah oath, if the defendant says 'let the claimant swear and receive', and the claimant demands Torah law', we do not reverse the oath. We reverse a mid'Rabanan oath. Mar bar Rav Ashi reverses even Torah oaths. If the one obligated to swear is Pasul, mid'Oraisa the claimant swears and collects. A mid'Rabanan oath is an enactment, and we do not make an enactment for an enactment. The Halachah does not follow Mar bar Rav Ashi.

Rif (Kesuvos 48a): When the claimant must swear to receive, he cannot reverse the oath onto the defendant. If the claimant says 'swear to me that you do not owe to me, or that you paid me, and be exempt', the defendant can say 'I need not swear. The ability to swear and be exempt helps me; I do not want this. You must swear to collect.' In cases like this, one can decline an enactment.

Rambam (Hilchos To'en 1:4): If one must swear mid'Rabanan to collect, he cannot reverse the oath onto the claimant. If he does not want to swear, he does not collect. My Rebbeyim said that he can say 'I decline Chachamim's enactment for me (to swear and collect). I want to be like any other claimant, who forces the defendant to swear Heses.' If the defendant wants to reverse it onto the claimant, the claimant must swear Heses in order to receive.

Magid Mishneh (DH v'Horu): This is proper reasoning. Surely he may lower his law and be like other claimants, who make the defendant swear Heses. Also the Ramah says so; this is primary.

Hagahos Maimoniyos (30): We do not enact for an enactment when both of these are against the defendant.

Magid Mishneh (2:1): A Pasul may not swear even Heses, even if the claimant wants to let him swear, for regarding Heses the opponent does not swear (and collect when the defendant cannot swear).

Lechem Mishneh (DH Kosav): Do not say that the enactment that a Chashud may not swear is for the claimant's benefit (and he may say 'I do not want it. Let him swear!') If it were for his benefit, we would not exempt a Chashud from swearing. Rather, the claimant would swear and receive!

Rashba (41a DH Ika): The Rif allows reversing only Shevu'as Heses. If the claimant says 'swear to be exempt', the defendant can say 'you may swear and collect. If you allow me to swear and be exempt, I decline', just like one may decline an enactment for his benefit. The Ramban supports this from Heses. It is primarily for the defendant, but he can say 'you may swear and collect. If not, I won't pay' (i.e. the claimant has the lower hand - PF.) All the more so, a claimant cannot reverse an oath to collect, which was enacted for him, onto the defendant!

Rosh (Kesuvos 9:25): If one cannot take a Shevu'ah mid'Oraisa, he must pay. A Pasul does not take a Shevu'ah mid'Rabanan, and need not pay, like it says in Kol ha'Nishba'in. The Rif wrote in a Teshuvah that if one admits that his document was partially paid, the borrower swears and he is exempt. We say that we do not enact for an enactment (to reverse a Shevu'ah mid'Rabanan), i.e. for Shevu'as Heses, but not for Shevuos of the Mishnah. Also, if we would say for Heses that the opponent of a Pasul swears and receives, the enactment for the enactment would cause one to pay. For a partially paid document, he swears and he is exempt. This is better than letting the Pasul receive without an oath. Do not say that mid'Oraisa and mid'Rabanan oaths differ about reversing the oath. Shevu'as Heses is mid'Rabanan, and we reverse it only from the defendant to the claimant. He says 'if I owe you, swear!' A claimant cannot reverse his oath to the defendant, and say 'if you are exempt, swear!' The defendant can say 'I do not want to swear. If you want, swear and collect. If not, go! I do not owe you.'

Maharshal (Kesuvos 88a DH Iy): This is not explicit in Shevuos. There, when the defendant cannot take a mid'Rabanan oath to avoid paying, we do not say that the claimant swears and collects. Tosfos holds that the same applies to an oath to swear and collect.

Maharsha (Kesuvos 88a DH Tosfos): Also Tosfos proves this from Perek Kol ha'Nishba'in (47a); the text 'Shevu'as ha'Dayanim (41a)' is wrong. If a defendant cannot take a Torah oath to be exempt, we say that the claimant swears and collects. We do not say so about a mid'Rabanan oath.

Terumas ha'Deshen (32): All agree that one can reverse a Shevu'ah mid'Rabanan (other than Heses), which requires holding a Chefetz (Kodesh item, e.g. Sefer Torah). Can one say 'you need not hold a Chefetz', so his opponent cannot reverse on him a severe oath with a Chefetz? It seems that he can pardon his rights. One who can impose an oath may let his opponent swear 'by the life of your head' (Sanhedrin 24a). Even after his opponent reversed the Shevu'ah to him, he can say 'swear a light oath to me, or I will swear a light oath to you.' The defendant still has the choice. He did not lose anything! This is unlike the Rosh (Shevuos 7:19), who says that if one was obligated to swear, and feared lest he be forced to swear about other matters through Gilgul, he may not say 'I will pay and not swear.' Rather, he pays all the claims, or he swears about everything through Gilgul. There, he wants to pay, to avoid swearing about the others. If he would pay just the first claim, the claimant would lose. The Rambam's Rebbeyim say that if Levi can swear to collect, he may say 'I waive this enactment. Let the defendant swear Heses.' The Rosh disagrees. Even if he says 'I am like a regular claimant, who obligates Heses', the defendant cannot reverse the oath. If not, the Rosh should have said that this is an advantage of a Torah oath (it can never be reversed). Even if one may not say 'make a light oath' after it was reversed onto himself, surely one may believe his opponent more than himself to let him swear.

POSKIM

Shulchan Aruch (CM 87:11): For a Shevu'ah mid'Oraisa, if the one who must swear said 'tell him to swear, and then I will pay', we do not force his opponent to swear. Also, if one must swear to receive, even though the oath is mid'Rabanan, he cannot reverse it on his opponent Bal Korcho (against his will).

Shach (30): If one witness testifies that a document was paid, the bearer must swear to collect, Rashi and Tosfos hold that he can reverse the oath; the witness does not help the borrower. The Rambam and Tur hold that he cannot reverse it. He can waive the enactment, and claim without the document. The witness exempts the borrower from swearing.

Shulchan Aruch (12): One who must swear mid'Rabanan to collect cannot reverse the oath onto the claimant Bal Korcho, but he can say 'I decline the enactment that Chachamim made for me. I want to be like any other claimant, who can force the defendant to swear Heses.' If the defendant wants to reverse it onto the claimant, we force the claimant to swear Heses if he wants to receive.

Darchei Moshe (6): The Terumas ha'Deshen says that the Rosh and Tosfos argue with the Rambam's Rebbeyim.

Rebuttal #1 (Bach 20): Perhaps the Rosh holds like the Tur (88:24), that even for a Torah oath, one can say 'swear Heses, and I will pay you.' The Rambam could agree. He just teaches that even for an oath to receive, which is an enactment, the claimant can reverse. Chachamim did not enact for an enactment, i.e. when both enactments are Bal Korcho.

Rebuttal #2 (Shach 35): The Tur concludes unlike this opinion (that even for a Torah oath, he can make the claimant swear Heses). However, the Terumas ha'Deshen's proof is invalid. In Kesuvos, the Rosh could not have said a Torah oath is better, for it cannot be reversed. After he pays her again, she could return the money and make him swear Heses that he paid her beforehand! Further, if one can ignore his document and force a Shevu'as Heses, the same applies if she needed to swear mid'Oraisa. Also, a supporting witness exempts from Heses (so she cannot reverse on him)! Rashi and Tosfos say that a Torah oath cannot be reversed. If a witness obligates an oath and it is reversed, he does not exempt from an oath. However, if a claimant demands an oath without a witness and it is reversed, the witness exempts him. All agree with the Rambam's law; it is obvious!

SMA (30): One can decline an enactment for his benefit, for we are not Mezakeh (acquire) for someone against his will