OPINIONS: Rebbi Yehudah and the Rabanan argue about the manner in which one must destroy his Chametz. The Rabanan say that one may destroy his Chametz in any manner, even by crumbling it up and throwing it into the sea or river. Rebbi Yehudah says that one must burn his Chametz.
What is the Halachah in practice?
(a) TOSFOS (27b, DH Ein) and the SEMAG rule that Bi'ur Chametz must be done through burning the Chametz, in accordance with the opinion of Rebbi Yehudah. These Rishonim rule like Rebbi Yehudah for two reasons. First, an anonymous Mishnah in Temurah (33a) follows Rebbi Yehudah's opinion. Second, Rebbi Yehudah derives his ruling from a valid source -- a Binyan Av from Nosar: just as Nosar may not be left over and must be burned, so, too, anything that must not be left over, such as Chametz, must be burned. (Even though Rebbi Yehudah himself maintains that an Asham Taluy, which also may not be left over, must be buried and not burned, the Binyan Av is still valid. With regard to an Asham Taluy, the Halachah follows the Rabanan who maintain that an Asham Taluy must be burned, and therefore Rebbi Yehudah's Binyan Av is valid to teach that just as Nosar must be burned, anything that may not be left over must be burned.)
(b) The ROSH (2:3) cites a number of authorities who dispute this conclusion, including the GE'ONIM, RABEINU YONAH, and the RAMBAM (Hilchos Chametz u'Matzah 3:11). They maintain that the Halachah follows the opinion of the Rabanan who say that Chametz may be destroyed in any manner and does not have to be burned.
How do they understand the Binyan Av, which seems to be irrefutable according to the opinion of the Rabanan?
The Rishonim suggest a number of ways in which the Binyan Av may be refuted. First, perhaps the Rabanan understand that the verse, "You shall burn the Nosar with fire" (Shemos 29:34), which teaches that only Nosar is to be burned and no other type of Isur is to be burned (24a), excludes Chametz as well, and that verse overrides the Binyan Av. Second, the Rosh suggests that the Rabanan differentiate between an item that is Kodesh and an item that is not Kodesh. Nosar is Kodesh and must be burned. The law with regard to Chametz, which is not Kodesh, cannot be derived from Nosar.
HALACHAH: The SHULCHAN ARUCH (OC 445:1) rules like the Rabanan, that Chametz may be disposed of in any manner. The REMA adds that the custom is to burn it.
However, the ROSH points out that whether the Halachah follows the opinion of Rebbi Yehudah or the opinion of the Rabanan is not consequential. Even Rebbi Yehudah agrees that "b'She'as Bi'uro" one may dispose of Chametz in any manner. The argument involves only "she'Lo b'She'as Bi'uro." According to TOSFOS, "she'Lo b'She'as Bi'uro" refers to after the sixth hour on Erev Pesach and throughout the festival (see Insights to Pesachim 27:1). Only during that time does Rebbi Yehudah argue that Chametz must be burned. In practice, of course, no one leaves over his Chametz until that time.
Rashi (according to the Rosh's understanding) explains that "she'Lo b'She'as Bi'uro" refers to the duration of the sixth hour but not before or after. According to Rashi, whether or not the Halachah follows Rebbi Yehudah is also virtually irrelevant, since people do not leave over their Chametz until the beginning of the sixth hour, because by then it is prohibited mid'Rabanan.
(Even if the Halachah does not follow the Rosh's understanding of Rashi, but rather Rashi maintains that prior to the sixth hour is also considered "b'She'as Bi'uro," this means merely that if one wants to destroy his Chametz (and not eat it or sell it) at that time, he should burn it. He certainly does not violate the Torah's command of "Tashbisu" if he gets rid of it by selling it or giving it away, as mentioned in Insights to Pesachim 27:1.)
The TUR (OC 445) suggests that there is an important difference between whether we rule like Rebbi Yehudah or like the Rabanan. According to Rebbi Yehudah, there is a specific Mitzvah to burn Chametz. The Gemara in Temurah (33a) teaches that whenever there is a specific Mitzvah to burn something which is Asur b'Hana'ah, that item's ashes are permitted. Once the item has been burned and the Mitzvah fulfilled, the item is no longer forbidden (because of the principle of "Na'asah Mitzvaso," see 26a). However, according to the Rabanan, there is no Mitzvah to burn Chametz. Consequently, even if one does burn it (on Pesach), its ashes remain Asur b'Hana'ah. Thus, a practical difference between whether the Halachah follows the opinion of Rebbi Yehudah or the Rabanan is whether the ashes of burned Chametz (which was burned "b'She'as Bi'uro") are Asur b'Hana'ah.
REBBI AKIVA EIGER challenges the Tur's conclusion. The Tur says that the Rabanan maintain that there is no Mitzvah to burn Chametz. How can the Tur say such a thing? The Mitzvah is to dispose of Chametz in any manner, which certainly includes burning! Since burning Chametz is a fulfillment of the Mitzvah to get rid of it, once the Chametz has been burned and the Mitzvah fulfilled, the ashes should be Mutar b'Hana'ah!
RABEINU CHAIM HA'LEVI SOLOVEITCHIK (Hilchos Chametz u'Matzah 1:3) explains that according to the Rabanan, burning Chametz cannot be considered "Na'asah Mitzvaso," such that the Chametz loses its Isur Hana'ah when it is burned. Since, according to the Rabanan, one may dispose of Chametz in any manner, the Mitzvah to destroy Chametz is a Mitzvah that rests on the person; he is obligated to get rid of his Chametz. It is not a Mitzvah on the Chametz that necessitates that the Chametz be burned. Accordingly, even if one burns the Chametz, no Mitzvah has been done to the Chametz itself. Rather, the person has fulfilled his own obligation. In order for its ashes to become permitted, the Chametz must have a Mitzvah done to it which is inherent in the Chametz itself. Rebbi Yehudah, who maintains that the Mitzvah is specifically to burn the Chametz, views the Mitzvah as one inherent in the Chametz itself: Chametz in a Jew's possession during Pesach must be destroyed through burning. Therefore, burning it removes the Isur Hana'ah from the ashes.


QUESTION: The Beraisa discusses three separate time periods with regard to the Isur of Chametz: before Pesach (after the sixth hour on Erev Pesach), during Pesach, and after Pesach. According to Rebbi Yehudah, before and after Pesach Chametz is forbidden by a Lav, and during Pesach it is forbidden by a Lav and eating it is punishable with Kares. According to Rebbi Shimon, before and after Pesach there is no Lav that forbids Chametz.
The Beraisa then states that "whenever Chametz is forbidden to be eaten (Asur b'Achilah), it is also forbidden to derive benefit from it (Asur b'Hana'ah)." The Gemara interjects that this statement "follows the Tana Kama," referring to Rebbi Yehudah.
How does the Gemara know that this is Rebbi Yehudah's statement? This statement is also true according to Rebbi Shimon. Rebbi Shimon agrees that whenever Chametz is forbidden to be eaten (that is, during Pesach), it is also Asur b'Hana'ah!
(a) The BA'AL HA'ME'OR explains that according to Rebbi Shimon, it would not have been necessary for the Beraisa to state explicitly that when Chametz is Asur b'Achilah, it is also Asur b'Hana'ah. Since there is only one time period when Chametz is Asur b'Achilah, it goes without saying that this is the time period in which Chametz is also Asur b'Hana'ah. If the Beraisa's intention is to teach that during Pesach Chametz is Asur b'Hana'ah according to Rebbi Shimon, then instead of saying, "Whenever Chametz is Asur b'Achilah, it is also Asur b'Hana'ah," it should simply have added to the words of Rebbi Shimon, "[During Pesach, Chametz is forbidden with a Lav and one is Chayav Kares,] and it is Asur b'Hana'ah." Rather, the Beraisa implies that there are different time periods when Chametz is Asur b'Achilah, and therefore it needs to say, "Whenever Chametz is Asur b'Achilah...," referring to all of the different time periods of the Isur Achilah of Chametz. This follows only the opinion of Rebbi Yehudah.
According to the Ba'al ha'Me'or, Rebbi Shimon maintains that after the sixth hour on Erev Pesach until sunset, one is permitted to eat Chametz. The Ba'al ha'Me'or clarifies this in the beginning of Pesachim, where he asserts that Rebbi Shimon maintains that although "Tashbisu" applies from midday on Erev Pesach, one fulfills the Mitzvah to destroy his Chametz by eating it.
(b) TOSFOS (DH Rebbi Shimon) suggests that Rebbi Shimon agrees that Chametz may not be eaten after the sixth hour, because the Mitzvah of "Tashbisu" is in effect then. Chametz is not forbidden because of a Lav, but because of the Mitzvas Aseh of "Tashbisu" that requires one to destroy his Chametz and, consequently, not to eat it. Chametz at that time is not Asur b'Hana'ah, because the Isur of Hana'ah is not included in the Mitzvah of "Tashbisu." Therefore, it would have been incorrect for Rebbi Shimon to have made the statement that "whenever Chametz is Asur b'Achilah, it is also Asur b'Hana'ah," because before Pesach, Chametz is Asur b'Achilah but Mutar b'Hana'ah.
(c) The RAN cites the opinion of the BA'AL HA'ITUR who says that according to Rebbi Shimon, Chametz is also Asur b'Hana'ah before Pesach, because the Mitzvah of "Tashbisu" includes an Isur Hana'ah as well as an Isur Achilah. According to the Ba'al ha'Itur, the question remains, why does the Gemara assume that the Beraisa's statement was said by Rebbi Yehudah and not by Rebbi Shimon? According to the Ba'al ha'Itur, the Beraisa's statement is true according to Rebbi Shimon as well. Moreover, it is not obvious that this is the view of Rebbi Shimon, because there is more than one period when Chametz is Asur b'Achilah, and thus it is necessary for Rebbi Shimon to teach this law.
The OR CHADASH answers that the words of the Beraisa imply that we know when Chametz is Asur b'Achilah, but we do not know when it is Asur b'Hana'ah. The Beraisa found it necessary to teach, "Whenever Chametz is Asur b'Achilah, it is also Asur b'Hana'ah." However, according to Rebbi Shimon, the Isur of Achilah and the Isur of Hana'ah before Pesach both come from the same source -- "Tashbisu." Accordingly, once we know about the Isur Achilah that is in effect before Pesach, we also know about the Isur Hana'ah; we cannot know the Isur of Achilah without knowing the Isur of Hana'ah, since they have the same source. Therefore, it would not be correct to teach (according to Rebbi Shimon) that "whenever Chametz is Asur b'Achilah, it is also Asur b'Hana'ah," because one prohibition does not depend on the other; they are derived from the same source.