QUESTION: The Mishnah (17a) states that "a Neder takes effect on another Neder," and it explains that this refers to an oath of Nezirus which takes effect on a pre-existing oath of Nezirus. The RAN explains that only Nezirus takes effect on another Nezirus, but a Neder cannot take effect on another Neder to make the person liable for two punishments for eating one prohibited object.

The Ran quotes other Rishonim who maintain that two Nedarim can take effect to make the person liable for two punishments, but he points out a number of difficulties with that opinion. If a Neder can take effect on another Neder, why does the Mishnah give the example of Nezirus? Moreover, why does the Gemara say that no verse is necessary to teach that two oaths of Nezirus take effect (consecutively) when a person says, "Hareini Nazir ha'Yom, Hareini Nazir l'Machar" ("I am a Nazir today, I am a Nazir tomorrow")? If two Nedarim can take effect on one object at the same time, the verse is necessary to teach that the two sets of Nezirus take effect simultaneously, such that one will be liable twice if he drinks wine during the first thirty days of his Nezirus, since both oaths of Nezirus take effect at the same time.

How do the other Rishonim answer these questions?

ANSWER: When the RAN cites the other opinion, he apparently refers to the opinion of the RASHBA. The Rashba explains that although a Neder takes effect on a Neder and a person will be liable twice for transgressing the "double" Neder, in the case of Nezirus the second Nezirus cannot take effect on the first. The first Nezirus must end before the second one can take effect. (See also SEFER HA'CHINUCH, Mitzvah 30.)

The reason for this is that when a person makes a Neder he creates an Isur; it is as though there is a new Lo Ta'aseh in the Torah which prohibits this object to him. Just as it is possible for the Torah to apply multiple prohibitions to a single act (such as five prohibitions for one who eats an ant; see Makos 16b), a person -- by repeating his Neder -- can create multiple prohibitions on one object. A Shevu'ah, in contrast, does not create a prohibition on the item, but it prohibits the person from doing the act of eating the item. Once the person is already prohibited from doing the act, he cannot become prohibited again. His second Shevu'ah in which he says that he will not do something does not take effect, because he is already obligated not to do the act. Nezirus is like a Shevu'ah in that it is a change in the status of the person (see MAHARIT #53-54, and as cited by the Shalmei Nedarim to 2b); once he is obligated to observe the laws of a Nazir, he cannot accept upon himself a second obligation to observe those laws. If, however, the duration of the second Nezirus extends beyond the first, then it takes effect (since "Ein Nezirus Pachos mi'Sheloshim Yom"; see previous Insight). According to Shmuel, even when the second Nezirus does not cover any more days than the first, the second Nezirus takes effect because it remains suspended until it finds a time at which it can take effect (which occurs the moment at which the first Nezirus ends).

The Rashba himself later retracts this view and explains, like the Ran, that a Neder cannot take effect on a pre-existing Neder.

QUESTION: The RAN writes that although a Shevu'ah cannot take effect on a pre-existing Shevu'ah, and, similarly, a Shevu'ah cannot take effect to prohibit something which the Torah already prohibits, a Neder can prohibit something which the Torah already prohibits. A Neder takes effect because a Neder is an Isur Cheftza, a prohibition on the object (besides the Isur Gavra of "Lo Yachel Devaro"), while the Torah's prohibition is an Isur Gavra, a prohibition on the person.

The Gemara in a number of places (Shevuos 22b, Makos 22a) explains that a Shevu'ah cannot take effect on something that is already prohibited by the Torah because the person is "Mushba v'Omed me'Har Sinai Hu, v'Ein Shevu'ah Chal Al Shevu'ah" -- the person is already bound by the Shevu'ah that he took at Har Sinai to observe the Torah, and a Shevu'ah cannot take effect on another Shevu'ah.

Why does the Gemara give the reason of "Ein Shevu'ah Chal Al Shevu'ah" and ignore the more general principle of "Ein Isur Chal Al Isur" (an Isur cannot take effect on a pre-existing Isur)? (NODA B'YEHUDAH OC 1:36; see also Insights to Shevuos 21:2.)

(a) The NODA B'YEHUDAH suggests that the principle of "Ein Isur Chal Al Isur" applies only to an Isur which the Torah itself teaches. It does not apply to an Isur which a person creates himself through a Shevu'ah.

The Noda b'Yehudah does not explain the logic for this distinction between an Isur of the Torah and an Isur a person makes through a Shevu'ah. What is the difference between a Shevu'ah and any other Isur in the Torah? Perhaps his logic is that an Isur Torah does not address a particular person and a particular situation. It does not need to take effect when another Isur already prohibits the act or the object (and, in fact, the Torah does not intend for the second Isur to apply when a first Isur already prohibits the act). A Shevu'ah, however, is created with the explicit intent that it apply to a particular person and a particular situation. Since the person who made the Shevu'ah did not intend that it be limited to an act which was not previously prohibited to him, perhaps it should apply even where a prohibition of the Torah (or another Shevu'ah) is already in force.

The Gemara therefore explains that a Torah prohibition is also a form of Shevu'ah, and therefore a second Shevu'ah cannot take effect and reinforce it.

(This logic may not apply to a Neder, since the prohibition created by a Neder is based on the Torah's prohibition of Korban. As such, it does not depend on the person's specific intent just as the Isur of Korban does not depend on his intent. That is why Tosfos in Shevuos (20b, DH d'Chi) applies the rule of "Ein Isur Chal Al Isur" to a Neder.)

(b) The KOVETZ HE'OROS in Shevuos (#33) suggests that a Shevu'ah does not create an actual prohibition per se. Rather, when a person makes a Shevu'ah to do a particular act, he asserts that such an act will certainly take place. If that act does not take place (that is, if he does not fulfill his Shevu'ah), he has lied. Accordingly, he is obligated to fulfill his Shevu'ah to avoid a retroactive lie.

In this respect, the Isur of a Shevu'ah is not similar to any other Isur of the Torah, since it takes effect neither on a particular object nor on a particular act. Rather, it forces the person to act in a certain way to prevent his words from becoming a lie retroactively. The reason an Isur cannot take effect when a pre-existing Isur is already in effect is that the second Isur adds nothing new to the Isur that already exists. A Shevu'ah, however, does add a new element to the Isur and does not merely reinforce the pre-existing Isur.

Both the approach of the Noda b'Yehudah and the approach of the Kovetz He'oros, however, are not consistent with the words of the Rishonim who explicitly refer to the principle of "Ein Isur Chal Al Isur" when they discuss a Shevu'ah. (See, for example, the BA'AL HA'ME'OR in Shevuos, end of third Perek.)

(c) The AVNEI MILU'IM (#12) suggests that the principle of "Ein Isur Chal Al Isur" does apply to a Shevu'ah. However, the principle of "Ein Isur Chal Al Isur" normally means that the second Isur cannot obligate the transgressor to receive a second set of Malkus or be obligated to bring a second Korban, but it does increase the strength and severity of the prohibition. The Gemara in Yevamos (33b) explains that because the prohibition becomes stronger, the transgressor is considered a more wicked Rasha, and when he dies he is buried among Resha'im of a similar degree of wickedness.

The Gemara teaches that when a Shevu'ah is made to prohibit something that is already prohibited by the Torah, not only does the Shevu'ah not make the person who transgresses the Isur liable for a second set of Malkus or a second Korban, it does not even strengthen the pre-existing prohibition. That is, the logic of "Mushba v'Omed me'Har Sinai" is more effective in preventing the Shevu'ah from taking effect than the logic of "Ein Isur Chal Al Isur."

(The basis for this distinction may be as follows. An ordinary Isur (for example, the Isur of "Eshes Ish") of the Torah is binding because the Torah mandates it. In contrast, a Shevu'ah is binding because a person makes a declaration, which the Torah empowers to create a prohibition. However, the Torah allows the declaration of a Shevu'ah to create a prohibition only under certain circumstances. When the act is already prohibited, the Torah does not allow the Shevu'ah to create an additional prohibition. "Ein Isur Chal Al Isur" means that the second Isur exists but it does not create liability for an additional punishment; the second Isur does make the act more severe, though. In the case of a Shevu'ah, however, the second Isur does not exist whatsoever (because the Torah does not allow for the creation of a prohibition under those circumstances), and therefore the principle of "Ein Isur Chal Al Isur" is not applicable.)

Why, though, according to the Avnei Milu'im, does Rava state that if a person makes two Shevu'os and then he annuls the first (through "She'eilah"), the second Shevu'ah takes effect? If the second Shevu'ah does not create even an Isur, it should be entirely ineffectual even after the person annuls the first Shevu'ah (as the Ran indeed suggests at the beginning of the Daf).

The answer is that "She'eilah," the annulment of a Shevu'ah, removes the first Shevu'ah retroactively ("l'Mafrei'a"). Accordingly, when the first Shevu'ah is annulled, it transpires that the second Shevu'ah was pronounced on an item that had no Shevu'ah on it, and the second Shevu'ah takes effect immediately from that time. In contrast, when a woman makes two Shevu'os and her husband annuls the first one with Hafarah, the second Shevu'ah does not take effect because a husband's Hafarah works only from now on ("mi'Kan ul'Haba") and not retroactively. Consequently, since at the time the second Shevu'ah was pronounced it created no Isur, it cannot take effect later when the first Shevu'ah is removed. (See HAGAHOS REBBI AKIVA EIGER to YD 238, who cites the MAHARAM MINTZ who reaches a similar conclusion based on Rashi in Shevuos 27a. However, Rebbi Akiva Eiger argues that even after the husband's Hafarah, the second Shevu'ah does take effect with regard to Malkus for "Lo Yachel Devaro," but not with regard to obligating her to bring a Korban for violating the Shevu'ah.)

(The Avnei Milu'im's explanation addresses why the Gemara does not say "Ein Isur [Chal Al Isur]" but rather "Ein Shevu'ah." However, it does not explain why the Gemara refers to the pre-existing Isur as a "Shevu'ah" ("Ein Shevu'ah Chal Al Shevu'ah") and not as an "Isur." If the Gemara's intent is to emphasize that a second Shevu'ah's inability to take effect on a pre-existing Isur is weaker than a second Isur's ability, it should say "Ein Shevu'ah Chal Al Isur" and not "Ein Shevu'ah Chal Al Shevu'ah." (See Insights to Shevu'os 21:2).)

The Avnei Milu'im points out a number of practical consequences of the fact that the Shevu'ah does not even strengthen the pre-existing Isur:

1. The obvious consequence is that the person who transgresses such a Shevu'ah is not buried among the more wicked Resha'im when he dies.

2. If a person is so ill that that the doctors have determined that he will die unless he eats Neveilah, he is permitted to eat Neveilah. What is the Halachah in a case in which the sick person had previously prohibited himself with a Shevu'ah from eating Neveilah? The law of Piku'ach Nefesh does not permit a person to violate his Shevu'ah, because he is able to repeal his Shevu'ah (through "She'eilah") instead. If the normal rule of "Ein Isur Chal Al Isur" would apply, the person would be required to have his Shevu'ah repealed before he eats the Neveilah (in order to minimize the severity of the transgression). The principle of "Mushba v'Omed," however, teaches that the Shevu'ah does not take effect at all and there is no need to repeal the Shevu'ah.

3. The Gemara (24a) states that according to Reish Lakish, the principle of "Isur Kollel" -- which normally enables a second Isur (which applies to more objects than the first Isur) to take effect on a pre-existing Isur -- does not apply to a self-imposed Isur like a Shevu'ah. The Avnei Milu'im asserts that this is because the principle of "Mushba v'Omed" is more limiting than the principle of "Ein Isur Chal Al Isur." An "Isur Kollel" takes effect only because the second Isur would be present even if it could not make the transgressor liable for a second set of Malkus for sinning with the object which is already prohibited by the first Isur. Since the second Isur does make him liable for Malkus with regard to other objects, the rule of "Isur Kollel" makes him liable for Malkus for sinning with the object which is already prohibited by the pre-existing Isur. A Shevu'ah, however, does not create an Isur at all on what was previously prohibited, and thus the principle of Isur Kollel does not apply.

4. The Avnei Milu'im suggests further that the reason why the Gemara mentions the principle of "Mushba v'Omed me'Har Sinai" ("Ein Shevu'ah Chal Al Shevu'ah") is to show that even if the Isur of the Torah and the person's Shevu'ah come into effect at the same time ("b'Vas Achas"), the Shevu'ah still does not take effect (even though, normally, when two Isurim come into effect at the same time they do take effect). For example, if he makes a Shevu'ah to prohibit himself from eating Neveilah, and afterwards his animal dies, even though the animal becomes forbidden to him because of the Isur Torah of Neveilah and because of his Shevu'ah at the same moment, the Shevu'ah does not take effect.

The logic for this distinction is similar to the logic for why the rule of "Isur Kollel" does not apply to a Shevu'ah. The reason why two ordinary Isurim take effect "b'Vas Achas" is that even if they would create no liability for Malkus (because of "Ein Isur Chal Al Isur"), nevertheless the Isurim co-exist and add severity to the act. In contrast, the principle of "Mushba v'Omed me'Har Sinai" prevents a Shevu'ah from taking effect when there is a pre-existing Isur. Therefore, even if the Shevu'ah and the cause for the other Isur occur simultaneously, only the Isur takes effect and not the Shevu'ah. (This may be true even according to those who disagree with Reish Lakish and maintain that a Shevu'ah does take effect when it is an "Isur Kollel.")

However, the Acharonim point out that the Gemara in Makos (22a) implies that even before the animal dies and becomes Neveilah, the Isur d'Oraisa of Neveilah was already in effect. Consequently, the Isur of Shevu'ah does not take effect at the same time as the Isur Torah even when the animal dies after the Shevu'ah was made. (MISHNAS REBBI AHARON, Yevamos 19; SHI'UREI REBBI SHMUEL, Yevamos 32:270)

(The Acharonim point out that the approach of the Avnei Milu'im is not consistent with the RAMBAM (Hilchos Shevu'os 4:10), who implies that the second Shevu'ah does take effect to make a more severe Isur.)

(d) Another answer may be suggested as follows. The rule that a Shevu'ah cannot take effect on a pre-existing Isur applies not only to a Mitzvas Lo Ta'aseh, but also to a Mitzvas Aseh. Just as a person cannot make a Shevu'ah to prohibit himself from doing an act which the Torah already prohibits him from doing, he cannot make a Shevu'ah to do an act which the Torah already obligates him to do. Perhaps the Gemara indeed could have said that the reason why one cannot make a Shevu'ah to prohibit himself from doing an act which a Mitzvas Lo Ta'aseh already prohibits is the principle of "Ein Isur Chal Al Isur" (indeed, the Rishonim here use this wording). However, this reason does not suffice to explain why one cannot make a Shevu'ah to do an act which a Mitzvas Aseh already obligates him to do. In such a case, the principle of "Ein Isur Chal Al Isur" does not apply, since there is no Isur in the first place. The Gemara therefore must give the reason of "Mushba v'Omed... v'Ein Shevu'ah Chal Al Shevu'ah" to explain why one's Shevu'ah does not take effect. (Indeed, the Gemara earlier (8a) and in Shevuos (25a) refers to a case in which one makes a Shevu'ah to fulfill a Mitzvas Aseh when it says the reason of "Ein Shevu'ah Chal Al Shevu'ah.") Since the Gemara must use that reason in reference to a Shevu'ah made to fulfill a Mitzvas Aseh, it also uses that phrase in reference to a Shevu'ah made to fulfill a Lo Ta'aseh.

Alternatively, it could be that a Neder can take effect to reinforce a negative Mitzvah because -- like the Ran says -- a Mitzvas Lo Ta'aseh is an Isur on the person, an Isur Gavra, while a Neder is an Isur Cheftza.

One might have thought that a Shevu'ah takes effect to reinforce an Isur d'Oraisa which is an Isur Cheftza, just as a Neder takes effect to reinforce an Isur d'Oraisa which is an Isur Gavra. As the Ran explains, a Neder is able to take effect to reinforce an Isur d'Oraisa because a Neder is an Isur Cheftza (an Isur on the object) while a Lo Ta'aseh is an Isur Gavra (an Isur on the person). The Gemara teaches that this is not true -- a Shevu'ah cannot take effect at all on an Isur d'Oraisa, because every Mitzvah in the Torah (even an Isur Cheftza, such as Neveilah) is also an Isur Gavra, as the Ran explains.

Perhaps this is the intention of the Gemara when it says "Mushba v'Omed me'Har Sinai" with regard to all of the prohibitions of the Torah. The Gemara means that even an Isur Cheftza, like Neveilah, is also an Isur on the Gavra ("Mushba v'Omed") and therefore a Shevu'ah cannot take effect on it. (See a similar answer in MALBUSHEI YOM TOV, volume II, Kuntrus Kal v'Chomer #7.) (M. Kornfeld)