QUESTION: The Gemara (85b-86a) relates an incident in which a relative of Rav Nachman sold the rights to collect her Kesuvah in the event that her husband dies or divorces her. She eventually was divorced, but she died before her husband gave her the Kesuvah. The Gemara says that the buyers approached the daughter of the woman to claim the Kesuvah money which her mother had sold to them. Rav Nachman suggested to the daughter a legal way to extract herself from the obligation to give the Kesuvah money to the buyers and keep it for herself. He told her to forgive the debt her father owes her (i.e. the Kesuvah). Even though her mother already sold the rights to collect that debt, a person is able to forgive and annul a debt that was already sold (see Insights to 85b).
The Gemara adds that even though she forgives the debt of the Kesuvah, she will still receive the money that she would have received from the Kesuvah since anyway she inherits her father's estate. The buyers of the Kesuvah will not be entitled to receive anything.
Why does the Gemara say that the buyers approached the daughter to collect the Kesuvah? Obviously, the Kesuvah was not yet in the hands of the daughter; it was still a debt which the father owed to her and which she had the ability to forgive and annul (as Rav Nachman instructed her to do). Why, then, did the buyer not go directly to her father and demand from him the money of the Kesuvah?
(a) RASHI (85b, DH Asu) explains that the daughter had already approached her father to ask him for the Kesuvah. The buyers, upon seeing her approach her father to collect the Kesuvah, approached her to inform her that the Kesuvah is not hers to collect. They did not actually attempt to collect the money from her.
(b) The ROSH and RITVA explain that not only did the girl's mother die, but the girl's father also died after he divorced his wife. Accordingly, the buyers needed to approach the daughter to claim the Kesuvah, because she was the heir to her father's property. This also explains why Rav Nachman was so certain that if she forgives the debt of the Kesuvah, she would still receive the money as a Yerushah, and he was not concerned that the father would use it up or that she would die before her father; since the father was already dead, she would immediately inherit his estate.
Why does Rashi not accept this simple explanation? The answer is that the Gemara in Bava Kama (109a) explains that a person may not forgive a debt which he owes to himself. When one owes a debt to himself it is considered as though it has been collected already and there is nothing to forgive. Therefore, if the girl's father already died, she cannot forgive the debt of the Kesuvah that he owes her, because -- as heir to his estate -- she owes herself the money of the Kesuvah and there is no debt to speak of that could be forgiven. It is as if she has already collected it, and thus the buyers are entitled to receive it.
The Rosh and Ritva, on the other hand, maintain that the Gemara teaches that a person is able to forgive a debt owed to himself and it is not considered to be collected already. They understand that this Sugya disagrees with the Sugya in Bava Kama which says that one may not forgive a debt which he owes to himself. (See the RASHBA in Bava Kama there who explains that even if the Gemara here is discussing a situation in which the father already died, it does not contradict the Sugya in Bava Kama, since the Gemara in Bava Kama is discussing a specific, limited situation when it says that one cannot forgive a debt owed to himself.)
The RAMBAN (81b) points out that Rashi's opinion that one cannot forgive a debt owed to himself answers a question posed by Tosfos (81b, DH Lo). The Gemara there says that if a man owes money to his brother and his brother dies with no children, rendering him a Yavam who must do Yibum with the wife of his creditor, the Yavam may not say that "since I inherit my brother's property through Yibum, I now owe myself money, and the money belongs to me [and is not Meshubad to the Kesuvah of the Yevamah]." Rather, the money must remain designated for the collection of the Kesuvah of the Yevamah.
Tosfos asks why the Yavam cannot simply forgive the debt. Since the living brother owes his deceased brother money, and the living brother inherits the property of -- and the debts owed to -- his deceased brother, he should be able to act on behalf of his brother and annul the debt (since the heir of a debt may forgive the debt).
According to Rashi, the answer is obvious. Once a person owes money to himself, it is considered as though he paid it already and it is too late to forgive the debt. The money therefore became Meshubad already towards the payment of the Yevamah's Kesuvah.