1) "KAVOD HA'MAKOM" AS GROUNDS FOR REGRET
QUESTION: In the Mishnah, Rebbi Eliezer states that when one wishes to have his Neder annulled, the Chacham may pose as a Pesach (grounds for regret) the question, "If you would have known that your parents would have been dishonored by your behavior, would you have made the Neder?" The Chachamim maintain that such a Pesach is not valid. Rebbi Eliezer agrees that such a Pesach is not valid when it is based not on the honor of parents but on the honor of Hash-m.
In the Gemara, Abaye explains that Rebbi Eliezer agrees that a Pesach based on the honor of Hash-m is not valid because no person would admit that he made the Neder knowing that it would anger Hash-m, and thus the question, "If you would have known that Hash-m would have been dishonored by your behavior, would you have made the Neder?" will not elicit an honest response.
The Mishnah later (65b), however, states that one may annul a Neder based on a Pesach which shows from a verse in the Torah that his Neder was wrong. For example, if one made a Neder to take revenge from someone who wronged him, he may annul the Neder based on the Pesach that had he known that the Torah forbids taking revenge he would not have made the Neder.
What is the difference between these two cases? In both cases, the person admits that he made the Neder against the word of Hash-m.
ANSWERS:
(a) The RAN explains that the Mishnah later refers only to types of Mitzvos which people tend to neglect. Accordingly, it is possible that one indeed would admit that he would have made the Neder anyway, and thus the Pesach has relevance.
(b) The ROSH explains that there is a difference between admitting that one would offend the honor of Hash-m and admitting that one would transgress a prohibition. No decent Jew would ever say that he does not care about the honor of Hash-m, but even a decent Jew might admit that he would have made the Neder even had he known that it involved a transgression.
(c) The ME'IRI points out that the Mishnah opens with a discussion about whether or not a Pesach for the honor of one's parents is a valid basis for the annulment of a Neder. The Chachamim -- who maintain that such a Pesach normally may not be used -- agree that if the person's Neder specifically expressed dishonor towards his parents, this type of Pesach may be used. The fact that he made a Neder against his parents shows that he is brazen and that he would admit, when asked, that he does not care if his Neder causes his parent disgrace.
The same reasoning applies in the case of a Pesach based on the dishonor of Hash-m. When one makes a Neder which is clearly counter to the Torah, he is believed to say he would have done it anyway even had he known that it was forbidden. He has already shown that he is brazen. However, when one makes an ordinary Neder, he would not say that he would have made the Neder even had he known that it dishonors Hash-m (even if he really would have made such a Neder).
The Me'iri proves this from the Yerushalmi here (according to his Girsa). The Yerushalmi states that if one makes a Neder that he will not sit in a certain Sukah or shake a certain Lulav, he may annul the Neder based on a Pesach that had he realized at the time he made his Neder that his words go against the honor of Hash-m he would not have made the Neder. This Pesach is valid because it is evident (from his initial Neder) that he is a brazen person who is not embarrassed to express his disrespectful feelings about the honor of Hash-m.
2. The BACH (YD 228:13) similarly writes that this is why the Mishnah later (65b) states that one may annul a Neder based on a Pesach "from what is written in the Torah." When the Pesach is based on something which is clearly written in the Torah, one whose Neder contradicts the Torah's teachings indeed would be honest with regard to whether he would have regretted his actions due to the verse. (Mordechai Zvi Dicker)

64b----------------------------------------64b

2) AGADAH: THE EVIDENCE THAT DASAN AND AVIRAM BECAME POOR
QUESTION: The Gemara discusses the verse which relates that Hash-m told Moshe that the people who wanted to kill him in Mitzrayim had "died" (Shemos 4:19). The Gemara asks that the ones who sought to kill him were Dasan and Aviram, but they were still alive. Reish Lakish explains that they were considered dead because they had become poor. A poor person is among the four types of people who are considered dead even in their lifetimes. Those four people are a poor person, a leper, a blind person, and one who has no children.
The RAN asks that if these four types of people are considered dead, how did Reish Lakish know that Dasan and Aviram were considered dead because they had become poor? Perhaps they were considered dead because they became lepers, blind, or had no children!
ANSWERS:
(a) The Ran (7b) explains that the impoverishment of Dasan and Aviram may be derived from other verses in the Torah. When Dasan and Aviram refused to go to Moshe Rabeinu, they proclaimed, "Even if you will blind the eyes of those people (i.e. us), we will not come up [to you]" (Bamidbar 16:14). The verse implies that they were able to see at that time and they were not blind. Similarly, the verse relates that they were punished "in the midst of all of Yisrael" (Devarim 11:616:), which proves that they could not have been lepers, since lepers must remain outside of the camp of Bnei Yisrael. They could not have been childless because that would not have been a reason for Pharaoh not to listen to them, as the Ran states. The only remaining possibility is that they became poor.
The SHEYAREI KORBAN (on the Yerushalmi here) asks that these proofs are not conclusive. It is possible that someone can become blind or smitten with leprosy and be cured. Although the verses relate that Dasan and Aviram were not blind or lepers at a later stage, there is no is no proof that they were not blind or lepers earlier.
(b) The SHEYAREI KORBAN explains instead that one who becomes blind or a leper may still maintain a high ranking in society when he is cured. As such, Hash-m would not have told Moshe to return to Mitzrayim if Dasan and Aviram had merely become blind or lepers, lest they be cured and still seek to kill him. However, one who loses his money cannot return to his former status of prestige; the disgrace of poverty makes him lose his former status. Therefore, Dasan and Aviram must have become poor, and that is why Hash-m called them "dead." (Mordechai Zvi Dicker)
3) "NOLAD" AS GROUNDS FOR REGRET
QUESTION: The Mishnah states that one cannot annul a Neder based on a Pesach of Nolad; he cannot say that he regrets making the Neder in light of circumstances that changed after he made the Neder. This is because at the time of the Neder these circumstances were not a factor. The RAN (end of 64b), however, quotes the Yerushalmi which states that if the new circumstances were foreseeable because they are common, Nolad may be used as a Pesach.
The RASHASH cites other sources to support the statement of the Yerushalmi. He asks, however, that the Gemara in Kesuvos (3b) seems to state otherwise. The Gemara there discusses a case in which a person says that he is giving a Get to his wife on condition that he does not return home by a certain date. The Gemara says that even if he returns to the outskirts of his city on that date but he cannot reach his home because the bridge to his city is out of service, the Get is valid, even though his fulfillment of the condition was due to circumstances beyond his control. Had he wanted to prevent the Get from taking effect as a result of an involuntary fulfillment of the condition due to circumstances which, although common, are beyond his control, he should have explicitly added to his condition, "... unless there are forced circumstances that prevent me from coming home." If, however, the involuntary circumstances that prevent his return are extremely uncommon (and no one is expected to consider that such a thing might happen), the Get certainly does not take effect.
Why may a common occurrence be used as a Pesach of Nolad, but it is not automatically included in one's condition in the case of a Get? Moreover, why may an uncommon occurrence not be used a Pesach of Nolad but it is automatically included in one's condition in the case of a Get? (The Rashash writes that there are many differences between the two cases, but he does not mention what those differences are.)
ANSWER: The ME'IRI explains that the reason why a Pesach of Nolad is valid only when the new occurrence is a common one is that a common occurrence is something which the Noder could have considered when he made the Neder. Since it is something that he might have considered, it is possible that he made a mistake when he made the Neder. However, if the new occurrence is uncommon, it is not something which he may say that he could have thought of at the time he made the Neder (and which would have prevented him from making the Neder). (Mordechai Zvi Dicker)