Gemara

We include from the Klal, due to "Lo Yash'iru Mimenu" (a Lav ha'Nitak l'Aseh), "Lo Sotzi." (If one took it out of the house, he must return it.)

Due to this Prat, we exclude Bal Yera'eh and Bal Yimatzei. (They are Nitak l'Aseh, i.e. Tashbisu.)

Rishonim

Rambam (Hilchos Chametz 1:3): One is lashed for Bal Yera'eh and Bal Yimatzei only if he acquired Chametz during Pesach, or fermented it, so that there is an action. If one had Chametz before Pesach, and Pesach came and he did not eradicate it, rather, left it in his Reshus, even though he transgressed these two Lavim, he is not lashed mid'Oraisa, since he did not do an action. He is lashed mid'Rabanan.

Magid Mishneh: A Tosefta (Makos 4:5) says that one is not lashed for leaving over Chametz or keeping Kil'ayim.

Kesef Mishneh: The Re'em asked that in Shoresh 9 (the introduction to Sefer ha'Mitzvos), the Rambam connotes that one is not lashed, for it is Lav shebi'Chlalos (different Isurim forbidden by one Lav)! One could resolve that he is lashed only once, even though he mentioned two Lavim. One could explain Semag (Lavim 77,78) similarly, even though he added [to the Rambam's words] "to be lashed for them. However, [if one is lashed only once,] why does he count them like two Lavim? I answer that Lo Yera'eh is only when he sees it. Sefer ha'Mitzvos (200,201) connotes like this.

Tosfos (Pesachim 28a DH v'Chametz): Above, the Gemara learned a Kal va'Chomer from Nosar, to which Bal Yera'eh and Bal Yimatzei do not apply. Here we say that "Lo Sosiru" is like Bal Yera'eh! The Ri answered that it is a Kal va'Chomer. One transgresses Nosar only the moment he leaves over. One transgresses Bal Yera'eh every moment.

Tosfos (Pesachim 29b DH Rav, citing the Ri): One who leaves over Chametz with intent to destroy it does not transgress. If not, why does R. Yosi say that there is Me'ilah for it? Once he redeems it, it is his. R. Yosi agrees that one may not own Chametz! Rather, surely he does not transgress. Lo Yera'eh is Nitak l'Aseh, so he does not transgress when he destroys it in the end.

Rivash (401 DH v'Im, brought in Beis Yosef 446 DH Kasav b'Hagahos): Chametz in Reshus ha'Rabim is like Hefker. One may not move it, for he acquires it through lifting it, and it is his, and he transgresses Bal Yera'eh and Bal Yimatzei.

Tosfos (95a DH bi'Frateha): Our Gemara supports the Ri, that Bal Yera'eh is Nitak l'Aseh.

Maharsha (95a DH b'Ferush Rashi): Our texts say that Bal Yera'eh and Bal Yimatzei are like "Lo Yash'iru Mimenu", i.e. a Lav ha'Nitak l'Aseh. Rashi's and Tosfos' text omitted it. Tosfos says that our Gemara connotes like the Ri. Our text explicitly says like the Ri! The Ri's Perush was written into the Gemara.

Note: It is not explicit in our text that if he destroys it in the end, he did not transgress.

Mishneh l'Melech: Tosfos (29b) does not mean that if he does not intend to destroy it, he is lashed. One is not lashed for any Lav ha'Nitak l'Aseh, even without intent to fulfill the Aseh, as long as he could fulfill it! Rather, Tosfos means that even though he is not lashed, he transgresses the Lav since he does not intend to fulfill the Aseh. If he intends to fulfill the Aseh, there is no Isur at all. See Tosfos 28a. (One transgresses Bal Yera'eh every moment, i.e. if he does not intend to destroy it.) Pesachim 95a explicitly says like the Ri. Rashi explains that the Torah forbids Chametz to be seen, and if it is seen, Tashbisenu (destroy it). The Mitzvah to destroy it applies the entire Mo'ed.

Hagahah: Tashbisenu must be eradicating it from the house, for once Chametz is forbidden, one cannot do Bitul. This is difficult. Rashi himself (4b DH b'Bitul) said that Tashbisu of the Torah is Bitul. There is no Torah source for Bi'ur, like we say (in 433:7? - PF). The Rambam holds like this, like the Beis Yosef says there.

Mishneh l'Melech: If so, why does the Rambam Mechayev lashes for acquiring Chametz or fermenting it, for he did an action? He is not lashed, because Bal Yera'eh is Nitak l'Aseh, even if he did an action! Rather, the Rambam rejected the Sugya on 95a. It says that Lo Sotzi'u is a Lav ha'Nitak l'Aseh. The Halachah does not follow this. We hold that if he was Motzi, it is Pasul and Asur, due to "u'Vasar ba'Sadeh Treifah Lo Socheilu." The Rambam relies on the Tosefta, which exempts from lashes one who leaves over Chametz or keeps Kil'ayim. I.e. it is because Ein Bo Ma'aseh, like keeping Kil'ayim.

Hagahah: the Rivash (401) explicitly holds like the Rambam. Devar Shmuel (38) asked the Mishneh l'Melech's question, and answered that it one acquired Chametz from a Nochri on Shabbos, which is the last day of Pesach, one cannot burn it [so it is not Nitak l'Aseh]. R. Tzvi Ashkenazi (42) questioned this, for the Rambam rules like Chachamim, that one may crumb it and cast it to the wind or cast it to the sea! I answer that the Magid Mishneh (3:8) forbids this on Yom Tov, and all the more so on Shabbos!

Note: Perhaps the Torah forbids casting it to the wind due to Zoreh. (See Magen Avraham below.) The Rambam rules like R. Yehudah, who obligates for Melachah she'Einah Tzerichah l'Gufah. However, the Magid Mishneh says that if he did not do Bitul, some permit on Yom Tov to burn it, or crumb it and cast it to the wind. Surely they forbid both methods equally on Yom Tov. Some say that the Torah permits all burning on Yom Tov due to mi'Toch, or due to "Lo Seva'aru Esh... b'Yom ha'Shabbos"!

Mishneh l'Melech: Why did he need to say that the seventh day was Shabbos? On a weekday, the Isur to crumb and cast to the wind on Yom Tov is only mid'Rabanan. Mid'Oraisa one may do Bitul, so it is Nitak l'Aseh. The Rashbam, Ran and Rema (321:12) permit crumbing bread, since there is no grinding after grinding. The Rambam disagrees (Kesef Mishneh 21:18). Further, if one grinds so finely in order to cast it to the wind, all obligate. This is a Toladah of grinding. This is clear from Tosfos Shabbos (114b DH Ela).

Note: Tosfos does not discuss grinding after grinding!

R. Chaim ha'Levi: R. Akiva Eiger questioned the Tur, who permits ashes of Chametz only according to R. Yehudah, who holds that Chametz must be burned. Chachamim forbid, for they allow Bi'ur in any way. Tosfos explains that ashes of Nikbarim (Isurim that we bury) are forbidden because there is no Mitzvah to eradicate them. If Chachamim hold that Bi'ur Chametz in any way is a Mitzvah, the ashes should be permitted! I answer that Tashbisu in other ways is so one will not have Chametz. Burning is a Mitzvah that takes effect on the Chametz, that it must be burned. Doing a Mitzvah on the Chametz permits the ashes, but a Mitzvah incumbent on the owner does not. The Rambam obligates lashes for Bal Yera'eh and Bal Yimatzei because it is not Nitak l'Aseh. Tashbisu is primarily an Aseh that one not have Chametz. This is like all matters forbidden with a Lav and Aseh, which are not considered Nitak l'Aseh. R. Yehudah, who says that the Mitzvah is to burn it, holds that it is Nitak l'Aseh. The Sugya on 95a is like him. The Rambam rules like Chachamim. Therefore, one is lashed.

Rashba (Teshuvah 1:178): Even though Chametz during Pesach is Asur b'Hana'ah, if one wants to acquire it, he acquires it to transgress for it and to permanently forbid it. We say similarly about Avodah Zarah.

Poskim

Shulchan Aruch (OC 446:1): One who finds Chametz in his house on Yom Tov covers it with a Kli, and burns it at night.

Magen Avraham (2): This is like Tosfos. Since he intends to eradicate it at the end, he does not transgress, for it is Nitak l'Aseh. One may cast it to the sea through a Nochri, for this is Shevus d'Shevus for the sake of a Mitzvah. Perhaps casting to the wind is mid'Oraisa.

Aruch ha'Shulchan (6 and 431:9): The Rambam agrees that it is Nitak l'Aseh. Amora'im argue about whether one is lashed for Lav ha'Nitak l'Aseh once it is impossible to fulfill the Aseh, or only if he was Mevatel (made it impossible to fulfill) it. The Rambam rules like the former opinion. At the last moment of Pesach, there is no time to eradicate it. The Lav is not Nitak l'Aseh, so one is lashed. Sha'agas Aryeh (80) rejected this, for the Rambam did not explicitly say so. I disagree.

Mishnah Berurah (6): The Shulchan Aruch connotes that this is even if he did not do Bitul, and he transgresses Bal Yera'eh. Many Poskim say that this is only if he did Bitul, and there is no Bal Yera'eh, just mid'Rabanan he must eradicate it lest he come to eat it. If he did not do Bi'ur, he casts it to a river or privy, or crumbles it and casts it to the wind (if possible, through a Nochri). Some permit even burning it, since it is somewhat a need of the day. The custom is like the Shulchan Aruch.

Kaf ha'Chayim (5): The same applies to Chametz after six hours on Erev Pesach that is on Shabbos.

Bi'ur Halachah (448:3 DH u'Bilvad): The Rivash (401) says that if one bought Chametz during Pesach on behalf of a Nochri, he transgresses Bal Yera'eh and is Chayav Makos, since there is no Shelichus for Nochrim [so he bought for himself].

Note: I.e. he transgressed an Aveirah for which there are Makos. If he intended to buy for the Nochri, he was not Mezid!

Avnei Milu'im (28:56): The Ritva connotes that there is no ownership of Isurei Hana'ah. The Rambam connotes that there is, for he is Mechayev one who buys Chametz during Pesach. One is liable for Chametz even though he does not own it (Bava Kama 29b), i.e. when it was already his before Pesach. Here, if one cannot acquire Chametz, he did nothing! The Rivash proved that one can acquire Isurei Hana'ah from a Yisrael who picked up idolatry. He acquires it, and then it cannot become Batel. One owns Isurei Hana'ah, but it is not considered in his Reshus, therefore he cannot be Mevatel it or Makdish it. This is like something stolen, before despair. The owner cannot be Mafkir it, sell it or be Makdish it.