(יט) שִׁבְעַ֣ת יָמִ֔ים שְׂאֹ֕ר לֹ֥א יִמָּצֵ֖א בְּבָתֵּיכֶ֑ם כִּ֣י ׀ כָּל־אֹכֵ֣ל מַחְמֶ֗צֶת וְנִכְרְתָ֞ה הַנֶּ֤פֶשׁ הַהִוא֙ מֵעֲדַ֣ת יִשְׂרָאֵ֔ל בַּגֵּ֖ר וּבְאֶזְרַ֥ח הָאָֽרֶץ׃
(19) No leaven shall be found in your houses for seven days. For whoever eats what is leavened, that person shall be cut off from the community of Israel, whether he is a stranger or a citizen of the country.
(ז) מַצּוֹת֙ יֵֽאָכֵ֔ל אֵ֖ת שִׁבְעַ֣ת הַיָּמִ֑ים וְלֹֽא־יֵרָאֶ֨ה לְךָ֜ חָמֵ֗ץ וְלֹֽא־יֵרָאֶ֥ה לְךָ֛ שְׂאֹ֖ר בְּכָל־גְּבֻלֶֽךָ׃
(7) Throughout the seven days unleavened bread shall be eaten; no leavened bread shall be found with you, and no leaven shall be found in all your territory.
(יט) לא ימצא בבתיכם. מִנַּיִן לִגְבוּלִין? תַּלְמוּד לֹוֹמַר "בְּכָל גְּבוּלֶךָ" (שמות י"ג); מַה תַּ"לֹ בְּבָתֵּיכֶם? מַה בֵּיתְךָ בִּרְשׁוּתְךָ, אַף גְּבוּלְךָ שֶׁבִּרְשׁוּתְךָ, יָצָא חֶמְצוֹ שֶׁל נָכְרִי שֶׁהוּא אֵצֶל יִשְׂרָאֵל וְלֹא קִבֵּל עָלָיו אַחֲרַיוּת (מכילתא):
(19) לא ימצא בבתיכם NO LEAVEN SHALL BE FOUND IN YOUR HOUSES — Whence may we derive that this applies also to the external properties which belong to you? From what Scripture states, (Exodus 13:7) “[Neither shall leaven be seen with thee] in all thy boundaries”. If this be so, why then need Scripture specify here “in your houses” (since this term is comprised in the more general term “in all thy boundaries”)? It is for the purpose of defining the latter term through the former. How is it the case of thy house? Everything contained in it is under thy control! So, too, the term “[leaven in all] your boundaries” means only such leaven as is in your boundaries and under your control, thereby excluding such leaven belonging to a non-Israelite as is deposited with an Israelite but for which he has accepted no responsibility (Mekhilta)
מתני׳ כל שעה שמותר לאכול מאכיל לבהמה לחיה ולעופות ומוכר לנכרי ומותר בהנאתו עבר זמנו אסור בהנאתו ולא יסיק בו תנור וכירים ר' יהודה אומר אין ביעור חמץ אלא שריפה וחכמים אומרים אף מפרר וזורה לרוח או מטיל לים:
MISHNA: For the entire time that it is permitted to eat leavened bread, one may also feed it to his domesticated animals, to non-domesticated animals, and to birds; and one may sell it to a gentile; and it is permitted to derive benefit from it. After its time passes, it is prohibited to derive benefit from it, and one may not even light an oven or a stove with leavened bread. With regard to the manner of removal of leavened bread, Rabbi Yehuda says: The removal of leavened bread is to be accomplished only through burning. And the Rabbis say: Burning is not required, as one may even crumble it and throw it into the wind or cast it into the sea.
(ו) נכרי שבא לביתו של ישראל [וחמץ] בידו אין זקוק לבער הפקידו אצלו חייב לבער ייחד לו בית בפני עצמו אין זקוק לו ישראל ונכרי שהיו באין בספינה וחמץ ביד ישראל ה"ז מוכרו לנכרי ונותנו במתנה וחוזר ולוקח ממנו [לאחר] הפסח ובלבד שיתנו לו במתנה גמורה.
(6) A Gentile who came to the house of a Jew and had chametz in his hand -- it is not incumbent upon him to remove him [from his house]. [But if the Gentile] deposited [the chametz] with him, he is required to remove it. [If the Jew] designated [a room in] his house [for the chametz to be deposited] by itself, it is not incumbent upon him [to remove it]. A Jew and a Gentile that were traveling on a ship and the Jew had chametz in his hand, behold, it is [deemed] sold to the Gentile and he gives it to him as a gift, and then he may return and buy it back from him for after Passover, as long as he [initially] gave it to him as an irrevocable gift.
בּה"ג על פּסחים
ובלבד שלא יערים
Baal Halachos Gedolos on Pesachim
Providing there is no Ha'arama
אמרו ליה רבנן לרב אשי חזי מר האי צורבא מרבנן ורב הונא ב"ר חיון שמיה ואמרי לה רב הונא בר' חלוון שמיה דשקל ברא דתומא ומנח בברזא דדנא ואמר לאצנועיה קמיכוינא ואזיל ונאים במברא ועבר להך גיסא וסייר פירי ואמר אנא למינם קמיכוינא אמר להו הערמה קאמרת הערמה בדרבנן היא וצורבא מרבנן לא אתי למיעבד לכתחילה:
On the topic of artifice, the Gemara relates that the Rabbis said to Rav Ashi: Master, observe this Torah scholar, and Rav Huna ben Rabbi Ḥayon is his name, and some say that his name is Rav Huna, son of Rabbi Ḥalvan, who took a slice of garlic and placed it in the spout of a barrel, and said: I intend to store it. He thereby stopped the spout on Shabbat. And similarly, he went and slept in a ferry on the river, and the ferryman sailed the ferry across the river, and he thereby crossed to the other side and inspected the fruit of his vineyard. He said: I intend to sleep. In this way, he crosses the river by boat on Shabbat, which is a prohibited activity. Rav Ashi said to them: Are you speaking of artifice? This is artifice employed to circumvent a rabbinic prohibition, and a Torah scholar will not come to perform the action ab initio without artifice. Therefore, there is no reason to prohibit him from doing so.
(ג) חָמֵץ שֶׁל יִשְׂרָאֵל שֶׁעָבַר עָלָיו הַפֶּסַח, אָסוּר בַּהֲנָאָה אֲפִלּוּ הִנִּיחוֹ שׁוֹגֵג אוֹ אָנוּס. וְאִם מְכָרוֹ אוֹ נְתָנוֹ לְעַכּוּ''ם שֶׁמִּחוּץ לַבַּיִת קֹדֶם הַפֶּסַח, אַף עַל פִּי שֶׁהַיִּשְׂרָאֵל מְכָרוֹ לְעַכּוּ''ם, וְיוֹדֵעַ שֶׁלֹּא יִגַּע בּוֹ כְּלָל אֶלָּא יִשְׁמְרֶנּוּ לוֹ עַד לְאַחַר הַפֶּסַח, וְיַחֲזֹר וְיִתְּנֶנּוּ לוֹ, מֻתָּר, וּבִלְבַד שֶׁיִּתְּנֶנּוּ לוֹ מַתָּנָה גְּמוּרָה בְּלִי שׁוּם תְּנַאי, אוֹ שֶׁיִּמְכְּרֶנּוּ לוֹ מְכִירָה גְּמוּרָה בְּדָבָר מוּעָט; אֲבָל מַתָּנָה עַל מְנַת לְהַחֲזִיר לֹא מְהָנֵי.
Chametz that belongs to a Jew which has been through Pesach, it is forbidden to derive any benefit from it, even if one left it accidentally or was forced. And if one sold it or gave it to a non-Jew who does not live with the Jew before Pesach, even though the Jew sold it to them and knows that the non-Jew won't touch it at all but rather will watch over it for the Jew till after Pesach, and then will return it to the Jew, despite all this it is permitted, as long as it was given fully without any conditions, or even if it was sold to them for a token sum. But, if it was given on condition that it be returned it does not work.
(כא) (כא) לא מהני - אע"ג דבכל התורה מתנה ע"מ להחזיר שמה מתנה אם נתקיים התנאי הכא הצריכו חכמים מתנה גמורה משום חומרא דחמץ.
It doesn't work - Even though in all other Torah matters a gift given on condition that it should be returned is considered a gift if the condition is met, here the wise ones needed it to be a full gift (without conditions) due to the seriousness of Chametz.
Rabbi Kalman Weinfeld, The History of Mechiras Chometz, https://www.ok.org/article/the-history-of-mechiras-chometz/
"The sale of chometz before Pesach is a common occurrence, practiced by Jews all over the world, but it didn’t start that way. The first sale of chometz was a regular sale, where a Jewish man sold his chometz to a non-Jew, just like any other product, but perhaps for a cheaper price to make it more attractive. After the sale was completed, the non-Jew became the owner of the chometz and it did not revert to the Jew after Pesach.There was a case where a Jew sold his chometz to a non-Jew with the understanding that it would be returned after Pesach. The Tosefta brings a case where the Jew needed to sell his chometz because he was on a ship in the middle of the sea during Pesach, but it seems that it was not done l’chatchila.
THE REQUIREMENT FOR A CONTRACT OF SALEIn the early 1600s, there was a significant change in the Polish-Jewish economy, which affected the Jewish community to a great extent. As a result, many Jews started producing and selling grain alcohols, which caused a new issue for Pesach. Until then, even when chometz was sold for a token payment, the chometz was removed from the Jew’s house until after Pesach. Needless to say, it was not very practical to do this with big warehouses of alcohol, which is meant to be stored for a long time in large quantities.Following this, the Bach ruled that the chometz could be sold to a non-Jew, even if it never left the premises of the Jew, as long as the Jew also sold the room where the chometz was located. This was a major turning point in the practice of selling chometz and brought another element to the sale – selling through a contract – because some poskim require a contract when selling real estate... The Russian law at that time stated that, unlike the sale of cattle, when alcohol was sold but not handed over right away, a contract was required. Having a contract for the sale of chometz makes the sale a true legal sale.
PAYING FOR THE CHOMETZAs mentioned, the price that the non-Jew pays for the chometz can even be a token value. This can be an issue when the chometz is of great value; perhaps the non-Jew will refuse to give it back. To tackle this issue, a different approach was taken. The chometz would be sold at or above market value, but the non-Jew would only pay a token amount at the time of the sale and the rest would be placed upon him as a debt. That way, if the non-Jew decided to keep the chometz, he would have to pay the full contracted price."
Reform Responsa to Searching, Burning, Selling Chametz
To destroy one’s chameitz becomes impractical and burdensome if one owns a large amount of leaven. The custom therefore arose for a Jew to sell his chameitz to a gentile before Pesach and to buy it back from him at the holiday’s conclusion. The roots of this practice extend back to tannaitic times. We learn in the Tosefta that “when a Jew and a Gentile are travelling on board ship, and the Jew has chametz in his possession, he may sell it to the Gentile and buy it back after Pesach, provided that the sale is a full and unencumbered transfer (matanah gemurah).”31 The development of this law, which apparently deals with a special case, into a regular and normal transaction is a long story that cannot be recounted here. We can simply point to the Shulchan Aruch and its commentaries, which accept as a matter of course that a Jew may sell chameitz to a gentile “even though the Jew knows the gentile and knows that the latter will guard the chameitz and return it to him after Pesach.”32 This custom is now universally practiced in traditional communities. In its most common form, all the Jews in a particular locale or congregation consign their chameitz to the rabbi or other notable, who then sells it all to a single gentile.33
This device of m’chirat (sale of) chameitz is effective because it is “full and unencumbered.” Although the leaven remains physically within the Jew’s property, its ownership is legally transferred to the gentile buyer in a transaction that meets all the formal halachic requirements of an act of sale. As such, it allows the householder to fulfill the mitzvah of the “removal” of chameitz, not necessarily under the terms of Exodus 12:15, which as we have seen may demand the physical removal of leaven, but under Exodus 13:7, which is understood to permit one to “see” chameitz that belongs to a non-Jew even though it remains within one’s property.34 Therefore, traditionally observant Jews hold that this form of sale is a perfectly valid means of discharging the Toraitic obligation to remove chameitz.
Reform Jews, of course, might well object to the fictitious aspect of this device. The sale may be fully “legal,” but it is not serious: neither the Jew nor the gentile intend that the chameitz be transferred to the latter’s permanent ownership. We might also ask whether the “sale” of chameitz is a better and more serious means of fulfilling the mitzvah than the process of bitul, nullification, described above. As is the case with sale, chameitz that is “nullified” remains within one’s physical—though not one’s legal—possession. Many authorities hold that the renunciation of chameitz fully meets the requirements of Exodus 12:15 and/or 13:7.35 The traditional halachah, it is true, does draw a distinction: while a Jew may make full use of chameitz “bought back” from a gentile after Pesach, leaven that is “renounced” is forbidden for use.36 The logic of this distinction, however, escapes us. The objection to bitul, say the authorities,37 is that one might declare falsely that “I annulled my chameitz before Pesach” when in fact one did not do so; therefore, although renouncing chameitz fulfills the Toraitic requirement, the Rabbis impose this penalty to forestall the possibility that one might evade the law. Yet what is bitul but a formal legal act that effects the legal—but not the physical—removal of chameitz from our possession? Is the “sale” of chameitz any different in its purpose and substance? It may be true that some Jews do not seriously intend to “renounce” their chameitz; it is certainly true, however, that none of them seriously intend to “sell” it.
We might also object to the sale of chameitz on the grounds that it requires the participation of a non-Jew in order that we can fulfill our own religious requirements. While Jews have for centuries relied upon gentiles to serve in such a capacity (the institution of the “Shabbos goy” comes readily to mind), the practice is inelegant at best and demeaning at worst. We prefer to fulfill our mitzvot on our own, especially in this case, when most authorities agree that the method of bitul allows us to meet the Torah’s demand that we remove our chameitz without incurring severe financial loss.
Therefore, “Reform Jews rarely resort” to the sale of chameitz; rather, they “make leaven inaccessible in their homes.”38 This is our way of renouncing our possession of chameitz, and we believe that we can do so with full seriousness and sincerity. While Reform Jews may wish to sell their chameitz, perhaps, again, out of solidarity with traditional Jewish practice, the standards of Reform Jewish observance do not require that they do so.
https://www.ccarnet.org/ccar-responsa/nyp-no-5756-9/