1) A DEBT GIVEN OVER TO BEIS DIN
QUESTION: The Gemara (36b) teaches that Rav Yosef's hand was like the hand of the poor; since he was the Gabai Tzedakah, when a person who was owed money pledged to give the money to the poor in front of him and the debtor, the money automatically was transferred to Rav Yosef. (See previous Insight.)
The Gemara quotes the statement of Rav Yehudah in the name of Shmuel as proof for this ruling. Rav Yehudah in the name of Shmuel said that orphans do not have to write a Pruzbul in order to collect debts owed to them after the Shemitah year. Since Beis Din is obligated to take care of the property of orphans, the money owed to the orphans is considered given over already to Beis Din to collect, and thus no Pruzbul is needed.
Why does giving one's documents over to Beis Din circumvent the prohibition of collecting loans after the Shemitah year has passed? RASHI in Gitin (37a, DH d'Tafsi Lehu) explains that Beis Din has the power to declare property Hefker (ownerless). Therefore, when the lender collects his debt that was handed over to Beis Din, he does not transgress the prohibition of "Lo Yigos" -- "Do not press [the borrower to pay back after Shemitah]."
Why does Rashi in Gitin need to say that Beis Din has the authority to make a person's property Hefker? It should suffice to say that they will collect the debt, and that is why they may collect after the Shemitah year. (AYELES HA'SHACHAR)
ANSWER: The AYELES HA'SHACHAR answers that the fact that Beis Din will collect the debt does not suffice to explain why they may collect it after Shemitah. After all, this should be no different from a person who sends his friend to collect his debts for him. Rashi therefore writes that Beis Din has the power to make a person's property Hefker. Beis Din has the authority to "take" (make ownerless) someone else's money even when there is no loan that needs to be collected. Accordingly, the prohibition of "Lo Yigos" does not apply to Beis Din, as "Lo Yigos" prohibits the lender from pressing the borrower for payment due to the loan itself. (Mordechai Zvi Dicker)
2) AN OX WHICH IS "MU'AD" FOR ONE THING AND NOT FOR OTHERS
OPINIONS: The Mishnah teaches that "an ox that is Mu'ad to [gore] its own type (oxen) and is not Mu'ad to a different type, or it is Mu'ad to people and is not Mu'ad to animals, or is Mu'ad to small animals and is not Mu'ad to large animals -- it pays full damage for what it is Mu'ad to gore, and it pays half-damage for what it is not Mu'ad to gore."
Rav Zevid and Rav Papa disagree about the correct text in the Mishnah. Rav Zevid asserts that the text is as it appears in the Mishnah, "and is not Mu'ad to...." From this wording he infers that only when the ox has been proven not to be a Mu'ad to other animals (that is, he saw them and did not gore them) is the owner liable only for Chatzi Nezek. Without proof that the ox is not Mu'ad to other animals, it is assumed to be a Mu'ad to them and the owner is liable for Nezek Shalem.
Rav Papa disagrees and says that the correct text does not include the word "and": "An ox that is Mu'ad to [gore] its own type is not Mu'ad to a different type." This means that even with no proof that the ox is not Mu'ad to other animals, it is not considered a Mu'ad to other animals.
The Gemara asks that according to Rav Papa the continuation of the Mishnah, "... it pays full damage for what it is Mu'ad to gore, and it pays half-damage for what it is not Mu'ad to gore," is superfluous. According to Rav Papa, this statement in the Mishnah is not part of the abovementioned cases, but is a statement of the law. Why does the Mishnah need to teach that when an ox damages something for which it is not Mu'ad, it pays only Chatzi Nezek? The law of Chatzi Nezek of Tam is already known! The Gemara leaves this question unanswered.
The Gemara asks another question from the second part of the Mishnah which quotes a question posed to Rebbi Yehudah, "This [ox} which is Mu'ad for Shabbosos and not Mu'ad for weekdays?" Rebbi Yehudah answered that for damage it does on Shabbos it pays Nezek Shalem, and for damage it does on weekdays it pays Chatzi Nezek. According to Rav Zevid, they were asking him what the law is in such a case. What, though, were they asking him according to Rav Papa? Without the word "and," their words are a statement and not a question, and Rebbi Yehudah responds with the exact same statement! The Gemara leaves this question unanswered as well.
How is the Mishnah to be understood according to Rav Papa, especially if the Halachah follows his view?
(a) The NIMUKEI YOSEF writes that the Halachah follows the view of Rav Papa. In the Mishnah, the Nimukei Yosef reconciles the difficulties with the text according to Rav Papa. He writes that even Rav Papa agrees that the text of the question posed to Rebbi Yehudah includes the word "and." As for the question from the first part of the Mishnah, apparently the Nimukei Yosef understands that the question is not a strong one, since perhaps the Mishnah merely omits the word "and" merely for consistency with the style of the rest of the Mishnah.
According to the Nimukei Yosef, Rav Papa should agree with Rav Zevid's ruling that a Mu'ad for Shabbos is a Mu'ad for weekdays unless proven otherwise. The RASHASH indeed quotes the MAHARSHA who says that that everyone must agree with this ruling.
(b) The RASHASH understands that Rav Papa and Rav Zevid do not argue about the actual text of the Mishnah. The Mishnah certainly reads "and is not Mu'ad." Rav Papa merely understands that when the Mishnah says "and" it means that the ox "is not a Mu'ad" -- it is not known that it is a Mu'ad for those other things.
When the Mishnah quotes the question posed to Rebbi Yehudah, "This [ox} which is Mu'ad for Shabbosos and not Mu'ad for weekdays," Rav Papa understands that they were asking what the law is in a case in which it is not known that the ox is not a Mu'ad for weekdays. (This answer does not contradict the Nimukei Yosef, but merely makes the explanation of the Mishnah more plausible.)
(c) The RAMBAM (Hilchos Nizkei Mamon 6:8) writes, "An ox that is Mu'ad for Shabbos is not Mu'ad for weekdays." This implies that it is not Mu'ad for weekdays even with no proof that this indeed is the case, unlike the explanation of the Nimukei Yosef.
The Rashash explains that the Rambam understands that once Rebbi Yehudah answers that there is a difference between Shabbos and weekdays in such a case, the case is similar to the case of an ox which is Mu'ad for oxen but not for other animals. In such a case, the ox is presumed not to be a Mu'ad unless proven otherwise. However, the Rashash concludes that this answer is somewhat difficult. (Mordechai Zvi Dicker)

37b----------------------------------------37b

2) ESTABLISHING A "CHAZAKAH" WITH INTERVALS
QUESTION: The Gemara quotes a dispute between Rav and Shmuel with regard to whether a woman establishes a Kevi'us by seeing Dam on the fifteenth day of one month, on the sixteenth day of the following month, and on the seventeenth day of the third month. Rav rules that this is considered a Kevi'us and she must therefore suspect that she will see Dam on the eighteenth day of the following month. Shmuel rules that this is not a Kevi'us since she did not see three times with a consistent interval between them. According to Shmuel, in order to establish a Kevi'us she must she Dam on the eighteenth day of the fourth month. If she sees Dam on that day, then she must suspect that she will see Dam on the nineteenth day of the fifth month. The Gemara says that Rav and Shmuel similarly disagree about whether an ox which gored in this sequence becomes a Mu'ad after the third goring (on the seventeenth day of the fourth month) or only after the fourth goring (on the eighteenth day of the fourth month).
The RASHBA questions the Gemara's assertion from the Beraisa quoted earlier (37a). The Beraisa states that if an ox gores one animal, sees another animal but does not gore it, sees a third animal and gores it, sees a fourth animal and but does not gore it, and then sees a fifth animal and gores it, the ox becomes a Mu'ad with intervals. The Beraisa clearly contradicts the view of Shmuel, who should require the ox to gore once more before it is declared a Mu'ad.
ANSWERS:
(a) The RA'AVAD (in BA'ALEI HA'NEFESH, Sha'ar Tikun ha'Vestos, ch. 3) cites an opinion that Shmuel indeed understands that the Beraisa means that in order for the ox to become a Mu'ad in this manner, it must gore a fourth time.
(b) The Ra'avad argues and gives a different answer to the question of the Rashba. He explains that there are two types of intervals: intervals which focus on the days on which the event happens, and intervals which focus on the period of the interval itself. For example, if a woman sees Dam on Rosh Chodesh three months in a row, Shmuel agrees that she must suspect that she will see Dam on the fourth Rosh Chodesh. Even though she has not established three actual intervals of thirty days (but only two intervals), the focus in this case is not the interval but the day; since she has seen Dam on the same day of the month for three consecutive months, she must suspect that she will see Dam on that day in the following (fourth) month. This is similar to the Beraisa's case of the ox, in which case the ox gores every other animal that it sees.
The second type of interval gives no significance to the day itself, but only to the amount of time that has passed between the days. In such a case, Shmuel requires three intervals; the fact that the event occurred a third time does not establish any concern that it will happen a fourth time in a similar pattern.
The Ra'avad explains that the dispute between Rav and Shmuel revolves around how to classify the case of Nidah. Is the focus only on the number of days in the interval, or is the focus also on the specific days of the month on which the event happens? Rav maintains that the specific days are significant, and therefore it is viewed like events that happen on the same days of successive months. Shmuel maintains that the focus is primarily on the interval. Accordingly, Shmuel rules that three intervals are required before she needs to suspect that she will see Dam after a fourth interval. (Mordechai Zvi Dicker)