Nedarim 17

תלמוד לומר להרע או להיטיב מה הטבה רשות אף הרעה רשות יצא נשבע לבטל את המצוה ולא ביטל שאין הרשות בידו

However, the verse states: “Or if anyone swears clearly with his lips to do evil, or to do good” (Leviticus 5:4). From the juxtaposition of evil and good it is derived that just as the doing of good, which is interpreted as obligating himself to take a positive action, is referring to a permitted activity, e.g., to eat, so too, the doing of evil, which is interpreted as prohibiting himself from something, refers only to that which is permitted, e.g., not to eat. This excludes one who takes an oath to nullify a mitzva and does not nullify it; he is not liable for violating the oath, as the permission to nullify it is not in his power.

חד קרא למיפטריה מקרבן שבועה וחד למיפטריה מן לאו דשבועה:

The Gemara answers that both verses are necessary. One verse: “To do evil or to do good,” which is stated in the context of the halakhot of offerings, is necessary to exempt him from bringing an offering for violating an oath, and one verse: “He shall not profane,” is necessary to exempt him from the prohibition for violating an oath.

מתני׳ יש נדר בתוך נדר ואין שבועה בתוך שבועה כיצד אמר הריני נזיר אם אוכל הריני נזיר אם אוכל ואכל חייב על כל אחת ואחת שבועה שלא אוכל שבועה שלא אוכל ואכל אינו חייב אלא אחת:

MISHNA: There is a vow within a vow. It is possible to impose an additional prohibition, by means of a vow, on an item that is already forbidden by means of a vow. But there is no oath within an oath. If one takes an oath twice with regard to the same action, the second oath does not take effect. How so? If one said: I am hereby a nazirite if I eat, and then repeated: I am hereby a nazirite if I eat, and then he ate, he is obligated to observe naziriteship for thirty days for each and every one of the vows, as both vows took effect. However, if he said: I hereby take an oath that I will not eat, and repeated: I hereby take an oath that I will not eat, and then he ate, he is liable to bring an offering for only one violation of an oath.

גמ׳ אמר רב הונא לא שנו אלא דאמר הריני נזיר היום הריני נזיר למחר דמיגו דקא מיתוסף יומא יתירא חיילא נזירות על נזירות אבל אמר הריני נזיר היום הריני נזיר היום אין חלה נזירות על נזירות ושמואל אמר אפילו אמר הריני נזיר היום הריני נזיר היום חלה נזירות עליה

GEMARA: Rav Huna said: They taught that there is a vow within a vow only where he said: I am hereby a nazirite today, and then he said: I am hereby a nazirite tomorrow. As since an additional day of naziriteship is added by the second vow, an additional thirty-day obligation of naziriteship takes effect upon the first term of naziriteship. However, if he said: I am hereby a nazirite today, and then repeated: I am hereby a nazirite today, a vow of naziriteship does not take effect upon a previous vow of naziriteship, and he must observe only one term of naziriteship. And Shmuel said that even if he said: I am hereby a nazirite today, I am hereby a nazirite today, a second vow of naziriteship takes effect with regard to him, as one can apply two obligations of naziriteship to himself one after the other.

ולרב הונא אדתנא אין שבועה בתוך שבועה ליתני יש נדר בתוך נדר ואין נדר בתוך נדר הריני נזיר היום הריני נזיר למחר יש נדר בתוך נדר הריני נזיר היום הריני נזיר היום

The Gemara asks: And according to Rav Huna, instead of teaching that there is no oath within an oath, drawing a distinction between a vow and an oath, let the mishna teach a narrower distinction between different vows, stating that there is a case of a vow within a vow, and there is a case in which there is not a vow within a vow. How so? If one says: I am hereby a nazirite today, I am hereby a nazirite tomorrow, in this case there is a vow within a vow. However, if one says: I am hereby a nazirite today, and then again says: I am hereby a nazirite today,

אין נדר בתוך נדר קשיא

in this case there is no vow within a vow. The Gemara concludes: This question is difficult, although it is not a conclusive refutation.

תנן יש נדר בתוך נדר ואין שבועה בתוך שבועה היכי דמי אילימא דאמר הריני נזיר היום הריני נזיר למחר דכוותה גבי שבועה שלא אוכל תאנים וחזר ואמר שבועה שלא אוכל ענבים אמאי לא חלה שבועה על שבועה

The Gemara raises several problems with the opinion of Rav Huna. We learned in the mishna: There is a vow within a vow, but there is no oath within an oath. What are the circumstances? If we say that the case of a vow within a vow is where one said: I am hereby a nazirite today, I am a hereby a nazirite tomorrow, that in the corresponding situation with regard to an oath within an oath, which will not take effect, is where one said: I hereby take an oath that I will not eat figs, and he then said: I hereby take an oath that I will not eat grapes, i.e., he took two separate oaths; if so, why does an additional oath not take effect where an oath was already made? It ought to take effect, as the second oath is not connected to the first one.

אלא היכי דמי דלא חלה שבועה על שבועה כגון דאמר שבועה שלא אוכל תאנים וחזר ואמר שבועה שלא אוכל תאנים דכוותה גבי נזירות היכי דמי דאמר הריני נזיר היום הריני נזיר היום וקתני יש נדר בתוך נדר קשיא לרב הונא

Rather, what are the circumstances in which a second oath does not take effect after an oath was already made? For example, where one said: I hereby take an oath that I will not eat figs, and he again said: I hereby take an oath that I will not eat figs. In the corresponding situation with regard to naziriteship, what are the circumstances? It must be a case where one said: I am hereby a nazirite today, I am a hereby a nazirite today; and the mishna teaches that in this case there is a vow within a vow. This poses a difficulty to the opinion of Rav Huna, who holds that in this case the second vow does not take effect.

אמר לך רב הונא מתניתין דאמר הריני נזיר היום הריני נזיר למחר דכוותה גבי שבועה דאמר שלא אוכל תאנים וחזר ואמר שבועה שלא אוכל תאנים וענבים דלא חיילא

The Gemara answers that Rav Huna could have said to you that the mishna is referring to a case where one said: I am hereby a nazirite today, I am hereby a nazirite tomorrow; that in the corresponding situation with regard to an oath where one said: I hereby take an oath that I will not eat figs, and then said: I hereby take an oath that I will not eat figs and grapes, the second oath does not take effect, as he had already taken an oath with regard to part of its content.

והאמר רבה שבועה שלא אוכל תאנים וחזר ואמר שבועה שלא אוכל תאנים וענבים ואכל תאנים והפריש קרבן וחזר ואכל ענבים הויא להו ענבים חצי שיעור ואין מביאים קרבן על חצי שיעור

The Gemara asks: But didn’t Rabba say that if one said: I hereby take an oath that I will not eat figs, and then said: I hereby take an oath that I will not eat figs and grapes, and he subsequently ate figs, violating the oath, and he then set aside an offering for the violation of an oath on a statement, and he then ate grapes, in this case the grapes that he ate are only a half-measure of the second oath. The inclusion of both figs and grapes in the oath indicates that his intention was to prohibit himself from eating both. Since he already set aside an offering for eating the figs, he is now considered as having eaten only grapes and as having violated only half of the oath. And therefore he is not liable to bring an offering for violating the second oath, as one does not bring an offering for a half-measure.

אלמא היכא דאמר שבועה שלא אוכל תאנים וחזר ואמר שבועה שלא אוכל תאנים וענבים מיגו דחל שבועה על ענבים חיילא נמי על תאנים רב הונא לא סבירא ליה כרבה

The fact that he is exempt from bringing an offering merely because he ate a half-measure indicates that the second oath took effect. Apparently, where one said: I hereby take an oath that I will not eat figs, and then said: I hereby take an oath that I will not eat figs and grapes, since the second oath can take effect with regard to grapes, as grapes were not included in the first oath, it takes effect with regard to figs as well. This poses a problem according to the opinion of Rav Huna, who would explain the mishna as teaching that the second oath in this case does not take effect at all. The Gemara answers: This is not a problem. Rav Huna does not hold in accordance with the opinion of Rabba, as Rabba was an amora and Rav Huna’s student.

מיתיבי מי שנזר שתי נזירות מנה את הראשונה והפריש קרבן ונשאל עליה עלתה לו שניה בראשונה

The Gemara raises an objection from a baraita: In the case of one who took two vows of naziriteship, counted the thirty days of the first term of naziriteship and set aside an offering at the end of its term, and then requested from a halakhic authority for dissolution of the vow before the offering was sacrificed, thereby rendering the offering unnecessary, the second term of naziriteship is counted for him instead of the first. He is considered as having fulfilled the second term of naziriteship during the period in which he observed the first one. Therefore, the offering that he set aside counts for the second term of naziriteship.

היכי דמי אילימא דאמר הריני נזיר היום הריני נזיר למחר אמאי עלתה לו שניה בראשונה הא איכא יומא יתירא אלא פשיטא דאמר הריני נזיר היום הריני נזיר היום

What are the circumstances? If we say that it is a case where he said: I am hereby a nazirite today, I am hereby a nazirite tomorrow, why is the second term of naziriteship counted for him instead of the first? Isn’t there an additional day in the second term of naziriteship that he has not yet observed, as the second thirty day term commences the day after the first thirty day period had commenced? How, then, is it possible that the second obligation was fulfilled through his observance of the first one? Rather, it is obvious that it is a case where he said: I am hereby a nazirite today, I am hereby a nazirite today,