Gemara

22b: (Mishnah): If one swore 'I will not eat', and he ate Neveilos, Treifos...', he is liable;

R. Shimon exempts.

23b: The case is, he swore 'I will not eat Neveilos....'

Question: Why is he liable? The oath of Sinai already forbids them!

Answer #1 (Rav, Shmuel and R. Yochanan): Because his oath is Chal (takes effect) on permitted food, it is Chal also on forbidden food.

Answer #2 (Reish Lakish): The Torah forbids only eating a k'Zayis of these things. His oath forbids eating any amount;

According to Chachamim, this is when he specified (any amount). According to R. Akiva, it is even without specifying.

R. Yochanan did not answer like Reish Lakish because he prefers to establish the Mishnah like Chachamim and R. Akiva.

Reish Lakish did not answer like R. Yochanan, for he holds that the principle of Kolel (if an Isur forbids something that was permitted, it also takes effect on things already forbidden) applies only to prohibitions that the Torah imposed, but not to Isurim that one imposes through oaths!

Question: Granted, Reish Lakish can say that R. Shimon exempts, for he obligates lashes for eating any amount of Isur, therefore the oath does not take effect. According to R. Yochanan, why does R. Shimon exempt? (The oath should take effect, for it is Kolel permitted and forbidden food!)

Answer: R. Shimon disagrees with the principle of Kolel.

(Beraisa - R. Shimon): One who eats a Neveilah on Yom Kipur is not liable for eating on Yom Kipur.

24b (Rava): According to the opinion that Isur Kolel Chal Al Isur, if one swore 'I will not eat figs', and later swore 'I will not eat figs or grapes', since the latter oath takes effect for grapes, it also takes effect for figs. Kolel applies even to an Isur (such as an oath) that one made by himself.

29a (Mishnah): The following are vain oaths... he swore not to fulfill a Mitzvah, e.g. not to dwell in a Sukah, take a Lulav or don Tefilin.

Rishonim

Rif and Rosh (12b and 3:26, citing the Yerushalmi): If one swore 'I will not eat Matzah', he may not eat Matzah on Pesach night. If he swore 'I will not eat Matzah on Pesach night, he is lashed and eats Matzah on Pesach night. If one swore 'I will not sit in shade', he may not sit in shade of a Sukah. If he swore 'I will not sit in shade of a Sukah', he is lashed and he sits in shade of a Sukah.

Ran (DH Gemara): A Shevu'ah takes effect to be Mevatel a Mitzvah through Kolel, if he will be passive. Since it takes effect on the other days, it takes effect also on Pesach night. A Shevu'ah not to eat Matzah Stam is called Kolel. An oath not to sit in shade of a Sukah is different, for Nedarim depend on how people speak. Stam unleavened bread is called Matzah, but a Stam shack is called a Sukah only if it is for the Mitzvah. The same applies to Lulav. This is why the Mishnah (29a) says that a Shevu'ah not to dwell in a Sukah, or take a Lulav is Shav, (for it is not Kolel).

Rambam (Hilchos Shevuos 1:6): If one swore to be Mevatel a Mitzvah, e.g. not to cover himself with Tzitzis, or wear Tefilin, or sit in a Sukah on Sukos or to eat Matzah on Pesach... it is a Shevu'as Shav (a vain oath).

Rambam (5:5): If one swore not to eat, and he ate Isurei Torah such as a k'Zayis of Neveilah or Sheratzim, he is exempt for Shevu'as Bituy (an oath to do or not do an action). If one swore to eat, and he ate Neveilah, he is exempt for Shevu'as Bituy. Since these are important to him, it is called eating.

Rambam (15): If one swore not to make a Sukah or wear Tefilin... he is lashed for Shevu'as Shav.

Rambam (18): If one swore not to eat Matzah for a year or two, he may not eat Matzah on Pesach night. If he ate, he is liable for Shevu'as Bituy. This is not Shevu'as Shav (a vain oath), for he did not swear not to eat Matzah (just) on Pesach night. Rather, he was Kolel times when eating Matzah is Reshus with when it is a Mitzvah. Since it takes effect on the other days, it takes effect also on Pesach night. The same applies to all similar cases, e.g. he swore never to sit in shade of a Sukah, or that he will not wear (any) garment for a year or two.

Rambam (Hilchos Nedarim 3:6): A Neder is Chal on Mitzvos like on Reshus (optional matters). If one forbade to himself Matzah on Pesach night or sitting in a Sukah on Sukos, or taking Tefilin, these are forbidden. If he ate, sat or took, he is lashed. The same applies to all similar cases.

Question (Lechem Mishneh): Even such a Shevu'ah is Chal, since it is Chal on Matzah, Sukah and Tefilin when there is no Mitzvah!

Answer (Lechem Mishneh): Nedarim depend on the way people speak. When people discuss eating Matzah, sitting in a Sukah, or taking Tefilin, they refer to the Mitzvah. The Rambam (Hilchos Shevuos 5:15) says that one who swears about one of these (Stam) is lashed for a vain oath. When the Rambam (5:18) discusses Kolel, he specifies 'never to sit in a Sukah.' The Ran says that a Stam Shevu'ah not to eat Matzah is Kolel; the Rambam disagrees. This is unlike the Kesef Mishneh. Why did the Rambam (Shevuos 1:6) specify a Shevu'ah not to sit in a Sukah on Sukos or to eat Matzah on Pesach? Perhaps this is not the exact words of the Noder.

Poskim

Shulchan Aruch (YD 236:5): If one swore 'I will not eat Matzah', he may not eat Matzah on Pesach night. If he swore 'I will not eat Matzah on Pesach night, he is lashed and he eats Matzah on Pesach night. If one swore 'I will not sit in shade', he may not sit in shade of a Sukah. If he swore 'I will not sit in shade of a Sukah', he is lashed and he sits in shade of a Sukah.

Beis Yosef (DH Kosav ha'Ran): The Ran says that some say that the Halachah does not follow the Yerushalmi, for the Bavli argues. He rejected them; we rely on the Yerushalmi. The Rivash (Sof 395) says that the Sugya of an oath to eat Neveilah connotes that a Shevu'ah to be Mevatel a Mitzvah is not Chal even through Kolel. The Ramban answered that this is only for an oath to do an Isur, for we do not tell one to sin to fulfill his oath, but an oath to transgress passively takes effect.

Shach (14): The Levush holds that an oath not to sit in a Sukah (without specifying) takes effect, unlike the Ran and Mechaber.

Gra (19): The text of the Yerushalmi is like the Mechaber.

Beis Yosef (DH Kosav Rabbeinu): The Rosh (Teshuvah 11:3) says that a Shevu'ah to fulfill or be Mevatel a Mitzvah mid'Rabanan takes effect.

Rema: Shevuos take effect on Mitzvos through Kolel only regarding a Mitzvas Aseh, but not regarding a Lav.

Shach (15): It does not depend on whether it is a Lav or Aseh, rather, whether one transgresses through action or inaction.

Shulchan Aruch (238:6): If one swore 'I will not eat Neveilos or slaughtered meat', or even if he swore Stam 'I will not eat', the Shevu'ah takes effect also on Neveilah. Similarly, if he swore 'I will not eat figs', and later swore 'I will not eat figs or grapes', both Shevuos take effect on figs.

Beis Yosef (DH u'Mah she'Chosav Oh): This is like Rashi, who explains according to Rava that a Stam Shevu'ah not to eat includes Neveilah, for it is edible, just forbidden. The Rambam exempts.

Gra (7): The Ran explains that a Stam Shevu'ah not to eat is only for proper food, but a Stam Shevu'ah to eat includes all foods.

Shulchan Aruch (239:4): A Shevu'ah is not Chal on a Mitzvah, e.g. 'I will not sit in a Sukah.'

Rema: This is only when he swore only about the Mitzvah. If he swore through Kolel (he also forbade Reshus), it is Chal also on a Mitzvah.

Ran (Teshuvah 73, cited in Beis Yosef DH v'Zeh): A Shevu'ah to pay the principal and the Ribis is Chal on the principal, so it is Chal even on the Ribis. However, one may not transgress Ribis in order to fulfill his Shevu'ah! If one swore to eat Neveilos (Chidushei Hagahos - and also Heter), surely we do not feed him Neveilos in order to fulfill his vow! Even if the Ribis is mid'Rabanan, Chachamim enforced their enactment like mid'Oraisa law, so one is passive (and does not pay, and transgresses).