1) RESTITUTION OF LAND FOR DAMAGES
QUESTION: RASHI (DH Hacha b'Mai Askinan) writes that when the Mazik (the person who caused damage) says that he has no money with which to pay for the damage he inflicted on another person's property, the Nizak (the one who suffered the damage) may take land from the Mazik in accordance with the value of the damage inflicted. Rashi makes a similar statement earlier (48b, DH Min ha'Idis), where he implies that the Mazik must pay with land only when he has no money. If he has money, he must pay with cash.
What is the source for Rashi's words? Why does the Mazik not have the option to pay with land even when he does have money? Also, why does Rashi choose to express this ruling here in Gitin (and not anywhere in Bava Kama, where it would be more appropriate)? (RASHASH 48b)
ANSWER: The CHASAM SOFER proves that the SHACH (CM 419:1) indeed maintains that when the Mazik has money or Metaltelin (movable property), he may not pay with land (if the Nizak so desires).
The NETZIV in MEROMEI SADEH quotes the RAMAH cited by the NIMUKEI YOSEF (Bava Kama 2a) who rules that if the Mazik has money, he must pay with money rather than with Metaltelin or with land. The Netziv explains (in HA'EMEK SHE'EILAH #111) how this ruling may be reconciled with the Gemara in Bava Kama (9a and 10a) which seems to contradict it.
Why does Rashi teach this law specifically in the Sugya here? The Chasam Sofer and Netziv point out that Rashi's intent here is to answer the question of TOSFOS (in DH Kegon). Tosfos asks why the only practical difference which the Gemara finds between the view of Rebbi Yishmael (who says "bid'Nizak Shaiminan") and the view of Rebbi Akiva (who says "bid'Mazik Shaiminan") is where the Ziburis (low quality) land of the Mazik is the same quality as the Idis (high quality) land of the Nizak. Why does the Gemara not suggest a practical difference in the opposite scenario -- where the Idis of the Mazik is like the Ziburis of the Nizak? According to Rebbi Akiva (who says that the Mazik pays according to the value of his own fields), it suffices for the Mazik to give his Idis. According to Rebbi Yishmael (who says that the Mazik must pay from a field of his that is as high in quality as the Idis of the Nizak), since the Mazik has no such field he may not pay with land. Instead, he must pay with money (since money is always considered to be as good as the best property; Bava Kama 9a). Tosfos leaves this question unanswered.
According to Rashi, the answer is clear. If the Mazik would have money, he would not be paying with land in the first place! Since he is trying to pay with land, he obviously has no money with which to pay, and therefore even according to Rebbi Yishmael he has no choice but to pay with the best of his lands, regardless of the quality of the Nizak's lands.

49b----------------------------------------49b

2) AN "AREV KABLAN"
OPINIONS: Mar Zutra rules that when a woman collects the Kesuvah after her husband dies, she collects from the Ziburis (low quality land) of the estate of the husband. If the husband is alive and divorces his wife, he must pay the Kesuvah from his Beinonis (medium quality land). Abaye challenges this ruling from the Mishnah (48b) which states that a Kesuvas Ishah is paid with Ziburis, Nizakin (damages) are paid with Idis (high quality land), and a Ba'al Chov (lender) is paid with Beinonis. If the person who must pay in all of these cases is dead and his heirs are the ones who are paying from his estate, in all of these cases the payment should be rendered from Ziburis! It must be that the Mishnah refers to a living man who pays the Kesuvah to his wife upon divorcing her, and yet the Mishnah says that he pays only from Ziburis.
Rav Acha bar Yakov answers that the Mishnah refers to a situation in which the father of the Mazik (or debtor, or husband) accepted upon himself to be an Arev (guarantor) to pay the obligations of the son in the event that his son is not able to pay his obligations. In such a case, even after the son dies the father must pay the son's obligations in the manner described in the Mishnah (Idis for Nizakin, Beinonis for a Ba'al Chov). However, the Kesuvah is still paid only with Ziburis since the obligation of the Kesuvah takes effect after the death of the son, and therefore there was no time during the son's lifetime at which he was obligated to pay the Kesuvah with his Beinonis. Since the son would have been obligated to pay his debt only with Ziburis (via his heirs), the father (who accepted upon himself to pay his son's obligations) also pays it only with Ziburis.
The Gemara adds that although a person who accepts Arvus, responsibility, for a man's obligation to pay a Kesuvah does not actually become obligated (but rather he accepted the "Arvus" merely for the sake of encouraging the woman to marry the man), the case of the Mishnah refers to a father who accepted to be an "Arev Kablan" for the Kesuvah-obligation of his son, and thus he indeed becomes obligated to pay the Kesuvah.
What is an "Arev Kablan?"
(a) RASHI (DH b'Kablan) and the RASHBAM (Bava Basra 47a) explain that the word "Kablan" denotes that the Arev received ("Kibel") money or an object on behalf of the borrower. Since the object passed through his hands, he has accepted a greater obligation towards the lender. TOSFOS (DH b'Kablan) explains that according to Rashi this is the meaning of "Kablan" whenever the Gemara discusses the concept.
In the case of an ordinary loan, it is clear that the Arev can become a Kablan by accepting the money which the lender gives to the borrower. However, in the case of a Kesuvah, the woman has not yet received her Kesuvah, and she is not giving anything to the Arev Kablan in order to obligate him to pay the Kesuvah when the time comes. How, then, can a person become a Kablan for a Kesuvah?
Rashi explains that one can become a Kablan for a Kesuvah in a case in which the husband designated certain Metaltelin items in his possession for the payment of the Kesuvah, and he gave them to his wife to hold until the time comes to collect the Kesuvah. If the wife hands over those Metaltelin to an Arev in order for him to return them to her husband, the Arev becomes an Arev Kablan.
The Gemara in Bava Basra (174a) gives different criteria for defining the difference between a Kablan and an Arev. The Gemara there says that when a person asks the lender to accept him as a Kablan for the loan, the wording he uses ("go give him money") differs from the wording used by an Arev ("lend him money"). Tosfos explains that Rashi understands that a Kablan requires both a different wording and physically accepting the money of the loan for the borrower.
However, Tosfos asks a strong question on Rashi's opinion from the Gemara there in Bava Basra. The Gemara concludes that "if the Arev accepts and passes on the loan with his own hands, the lender has no claim on the borrower at all (Ein Lo l'Malveh Al ha'Loveh Kelum)"; rather, he must collect directly from the Arev and not from the borrower. Accordingly, when he accepts the loan directly from the lender, he is not a Kablan at all since in the case of a Kablan the lender may collect from the borrower if he so chooses, as is clear from the Gemara here (see Rashi, DH Is Lei Nichsei).
Tosfos answers that the case in Bava Basra in which the lender cannot collect from the borrower is where the Arev Kablan took money from the lender and gave it to the borrower (which is not the same as the case here; see also Tosfos ha'Rosh).
Tosfos' intention here is not clear (see MAHARSHA, MAHARAM, and PNEI YEHOSHUA). Perhaps Tosfos means that the case in Bava Basra is when the Arev Kablan said, "Lend me money," and then he went and lent the money that he received to the borrower. He did not request the money for the borrower but rather for himself. In this case, the Arev certainly is the only one who is obligated to pay back the loan to the lender (see ALIYOS D'RABEINU YONAH in Bava Basra 174a). In the case of the Gemara here, however, the father requested from the woman the Metaltelin that were reserved for the Kesuvah in order to "return" them to his son, as Rashi writes.
(b) The RASHBA and RITVA, however, explain that a Kablan becomes a Kablan simply because of the wording he uses when he accepts the Arvus. This follows the simple reading of the Gemara in Bava Basra. It is not necessary for him to physically accept any money or object. The reason he is called a Kablan is because he has accepted ("Kibel") responsibility to pay back the loan. If he physically accepts the loan itself, his obligation is much greater than that of an Arev Kablan, and the lender may collect only from him and not from the borrower (as Tosfos here cites from Bava Basra 174a).
The Rashbam himself (in Bava Basra 173b, DH Kablanus) seems to retract what he wrote earlier in Bava Basra and sides with the other Rishonim.
(c) The TOSFOS HA'ROSH and the RASHBA (in the name of Tosfos) compromise and explain that, normally, a person becomes a Kablan based on the wording he uses and not because he physically accepts the loan. However, the wording alone is not enough to make a person a Kablan for a Kesuvah (because he does not cause any loss to the wife any by accepting responsibility, since she has not handed over any money as a result of his promise to pay back). Therefore, in order to become an Arev Kablan for a Kesuvah, it is necessary for the wife to have received Metaltelin which were designated for the payment of her Kesuvah and to return them based on the promise of the Arev. Only then does one become an Arev Kablan.