1) FRUIT THAT WAS GUARDED DURING THE SHEMITAH YEAR
QUESTION: The Beraisa states that when a Nochri sells fruit in the market during the Shemitah year and proclaims that "these fruits are of Azeikah," he is not believed to prohibit the fruit. His description of the fruit as "fruits of Azeikah" is assumed to be merely an attempt to impress potential buyers with its quality, and thus he likely is lying.
RASHI (DH Shel Azeikah) cites an explanation that "Azeikah" refers to a field protected by a fence during the Shemitah year. Since the fruits of that field were guarded during the Shemitah year, they are forbidden. Rashi rejects this explanation on the grounds that guarding fruits during the Shemitah year does not render them forbidden.
The Toras Kohanim, however, states explicitly that the verse, "Invei Nezirecha Lo Sivtzor" -- "Do not harvest the grapes that you guarded" (Vayikra 25:5), means that one is permitted to harvest only fruit that is Hefker, ownerless, which implies that fruit guarded during Shemitah is forbidden. How does Rashi understand the teaching of the Toras Kohanim?
(a) RASHI, who maintains that there is no prohibition against eating fruit that was guarded during Shemitah, apparently understands that the Toras Kohanim does not mean that the fruit becomes prohibited when it is guarded during Shemitah. Rather, the Toras Kohanim means that one is not permitted to guard the fruit but must leave it as Hefker. If, however, one transgressed and guarded the fruit and did not make it Hefker, he is permitted to eat it.
(b) TOSFOS in the name of RABEINU TAM writes that fruit guarded during Shemitah indeed becomes prohibited to be eaten. This ruling is in accordance with the straightforward understanding of the Toras Kohanim.
(c) TOSFOS in Menachos (84a, DH Shomrei) explains that the verse forbids harvesting fruit that was guarded. The verse does not forbid eating such fruit. (Rashi may understand that this is the intention of the Toras Kohanim as well.)
Tosfos adds that the Rabanan prohibited harvesting even fruit of Hefker (in the normal manner of harvesting) during Shemitah, and they prohibited eating fruit that was guarded during Shemitah. (See also Tosfos to Sukah 39b, DH ba'Meh.)
2) INTERROGATING WITNESSES FOR "EDUS ISHAH"
QUESTION: The Gemara cites a Beraisa in which the Tana Kama states that the witness who testifies about the death of a woman's husband does not need to be interrogated with Derishah v'Chakirah. Rebbi Tarfon disagrees and says that the witness must be interrogated.
The Gemara explains the logic of the dispute as follows. The Torah requires Derishah v'Chakirah for Dinei Nefashos, cases of capital punishment. Although the Torah also requires Derishah v'Chakirah for Dinei Mamonos, cases of financial matters, the Rabanan removed that requirement in order to encourage people to be more willing to lend money to those in need ("she'Lo Tin'ol Deles Bifnei Lovin"). The Tana'im who disagree about whether "Edus Ishah" (testimony about the death of a woman's husband) needs Derishah v'Chakirah disagree about whether permitting a woman to remarry is comparable to Dinei Nefashos or to Dinei Mamonos. Perhaps it is comparable to Dinei Nefashos because a woman who lives with another man while her husband is still alive is Chayav Misah. On the other hand, perhaps it is comparable to Dinei Mamonos because it involves giving the woman the money of her Kesuvah.
Why should "Edus Ishah" be comparable to a case of Dinei Mamonos merely because it involves payment of the Kesuvah? The primary subject of the case is whether the woman may remarry or not. The Kesuvah is merely a secondary consequence of the primary ruling in the case. Why should the secondary consequence alter the status of the case and render it a case of Dinei Mamonos?
(a) The RAMBAN answers that when the Rabanan enacted that Derishah v'Chakirah is not required in cases of Dinei Mamonos, they also sought to enact a leniency with regard to a woman's Kesuvah (which is also Dinei Mamonos). In order to allow the woman to collect her Kesuvah without Derishah v'Chakirah, the Rabanan needed to enact the leniency with regard to the marriage in general, because the Kesuvah stipulates that "when she gets married to someone else, she will receive her Kesuvah." Since she receives her Kesuvah only if she is permitted to remarry, the Rabanan permitted her to remarry without Derishah v'Chakirah.
(Although the reason why the Rabanan were lenient in all other cases of Dinei Mamonos is "she'Lo Tin'ol Deles Bifnei Lovin" -- which does not apply in the case of a Kesuvah, the Rabanan still wanted to be lenient with the Kesuvah in order not to differentiate between monetary laws ("Lo Plug"), or because of "Chen" -- to help ensure that the woman will be committed to her husband, with the knowledge that it is easy for her to get her Kesuvah.)
(b) The RAMBAN suggests a second explanation. He points out that "Edus Ishah" is not exactly like Dinei Nefashos, because the case involves whether the woman may remarry and not whether she is to be punished. On the other hand, "Edus Ishah" is not exactly like Dinei Mamonos, because the subject of the testimony is the marriage, and not the Kesuvah. Therefore, the question is, which type of case does "Edus Ishah" more closely resemble?
The Tana who rules that "Edus Ishah" does not need Derishah v'Chakirah maintains that since today Dinei Mamonos are far more common than Dinei Nefashos (Beis Din does not judge cases of Dinei Nefashos today), it is logical to assume that the Rabanan enacted that "Edus Ishah" be treated like Dinei Mamonos, the more common type of case. (That is, "Edus Ishah" is compared to Dinei Mamonos not only because of the Kesuvah, but because Dinei Mamonos is the more common type of case.)
(c) The RITVA in the name of the RE'AH writes that mid'Oraisa "Edus Ishah" does not need Derishah v'Chakirah. The verse mentions the requirement for Derishah v'Chakirah only with regard to Dinei Nefashos and Dinei Mamonos, but not with regard to "Edus Ishah." (The Gezeirah Shavah of "Davar Davar" from Dinei Mamonos does not apply to "Edus Ishah" to teach that it needs Derishah v'Chakirah.)
Why, then, does Rebbi Tarfon maintain that "Edus Ishah" requires Derishah v'Chakirah? The Re'ah explains that mid'Oraisa the testimony for the Kesuvah indeed requires Derishah v'Chakirah (since it is Dinei Mamonos). However, the Rabanan enacted that in all other cases of Dinei Mamonos, Derishah v'Chakirah is not required because of "she'Lo Tin'ol Deles." They applied that enactment to testimony about the Kesuvah because of "Lo Plug." However, since this basis for the exemption from Derishah v'Chakirah is weak, the Rabanan will utilize any valid reason to require Derishah v'Chakirah for the Kesuvah. Accordingly, the Rabanan instituted Derishah v'Chakirah for "Edus Ishah" because of its similarity to Dinei Nefashos so that the testimony -- which affects the Kesuvah -- will have Derishah v'Chakirah.
The Re'ah apparently follows his own reasoning as expressed elsewhere. The Re'ah earlier (cited by the Ritva to 88a; see Insights there), proposes the novel suggestion that a single witness is believed mid'Oraisa to testify about the death of a woman's husband. He is believed mid'Oraisa because he is afraid to lie; he knows that if he lies he will be discovered eventually when the husband returns alive ("Milsa d'Avida l'Giluyei"). This logic provides sufficient grounds to assume that he is not lying.
The Re'ah may understand that an enactment of the Rabanan is not sufficient reason to be lenient with testimony of "Edus Ishah," a case which involves severe Torah prohibitions. Therefore, the requirement for Derishah v'Chakirah cannot be mid'Oraisa for "Edus Ishah," because if it would be required mid'Oraisa the Rabanan would not have the prerogative to be lenient and remove that requirement. (The logic of "Milsa d'Avida l'Giluyei" does not suffice to exempt "Edus Ishah" from the requirement of Derishah v'Chakirah, since the Gemara here does not mention that possibility.)
(d) The RASHBA infers another answer to this question from the words of the RAMBAM (Hilchos Gerushin 13:28). The Rambam writes that the reason why "Edus Ishah" does not need Derishah v'Chakirah is that the Rabanan were lenient due to their desire to prevent women from becoming Agunos ("Hataras Agunah"). Why does the Rambam give a reason which is different from the reason the Gemara itself gives? The Gemara says that "Edus Ishah" does not need Derishah v'Chakirah because it is considered Dinei Mamonos, since it involves the Kesuvah.
The Rambam must mean that the Kesuvah does not render "Edus Ishah" a case of Dinei Mamonos. Rather, "Edus Ishah" clearly is a case of Dinei Nefashos, since it involves permitting an Eshes Ish to remarry. However, out of concern for Agunos, the Rabanan instituted that since the Kesuvah introduces an element of Dinei Mamonos into "Edus Ishah," the entire case may be treated like Dinei Mamonos, with no need for Derishah v'Chakirah. (Others explain the Rambam's intention differently. See footnote #109 to the Rashba.)