The Torah (Exodus 13:7) states: "No chametz shall be seen for you." Perhaps, if it were buried or entrusted to a gentile, he would not transgress the commandment? The Torah (Exodus 12:19) states: "leaven should not be found in your homes," [implying] even if it is buried or entrusted.
Perhaps he would only transgress [the commandment] when chametz is [found] in his house, but if it were outside his house, in a field or in another city, he would not violate [the commandment]? The Torah states (Exodus 13:7): "[No leaven shall be seen for you] in all your territory" - i.e., in all your possessions.
Perhaps a person will be obligated to remove from his property chametz that belongs to a gentile or that was consecrated? The Torah states (ibid.): "No [leaven] shall be seen for you." [We may infer]: You may not see your own [leaven]. However, you may see [leaven] belonging to others or which was consecrated.
אכָּתוּב בַּתּוֹרָה (שמות יג ז) "לֹא יֵרָאֶה לְךָ חָמֵץ". יָכוֹל אִם טָמַן אוֹתוֹ אוֹ הִפְקִיד אוֹתוֹ בְּיַד עַכּוּ''ם לֹא יִהְיֶה עוֹבֵר תַּלְמוּד לוֹמַר (שמות יב יט) "שְׂאֹר לֹא יִמָּצֵא בְּבָתֵּיכֶם" אֲפִלּוּ הִפְקִידוֹ אוֹ הִטְמִינוֹ. יָכוֹל לֹא יִהְיֶה עוֹבֵר אֶלָּא אִם כֵּן הָיָה הֶחָמֵץ בְּבֵיתוֹ אֲבָל אִם הָיָה רָחוֹק מִבֵּיתוֹ בַּשָּׂדֶה אוֹ בְּעִיר אַחֶרֶת לֹא יִהְיֶה עוֹבֵר תַּלְמוּד לוֹמַר (שמות יג ז) (דברים טז ד) "בְּכָל גְּבֻלֶךָ" בְּכָל רְשׁוּתְךָ. יָכוֹל יְהֵא חַיָּב לְבַעֵר מֵרְשׁוּתוֹ חָמֵץ שֶׁל עַכּוּ''ם אוֹ שֶׁל הֶקְדֵּשׁ תַּלְמוּד לוֹמַר (שמות יג ז) (דברים טז ד) לֹא יֵרָאֶה לְךָ שֶׁלְּךָ אִי אַתָּה רוֹאֶה אֲבָל אַתָּה רוֹאֶה שֶׁל אֲחֵרִים וְשֶׁל גָּבוֹהַּ:
[From the above,] you can learn that chametz belonging to a Jew which was left in his possession, even though it is buried, is located in another city, or is entrusted to a gentile, causes him to violate [the commandments]: "[leaven] shall not be seen" and "[leaven] shall not be found."
Chametz that either was consecrated or belongs to a gentile, and is located within a Jew's property, even if it was with him at home—behold, this is permitted, for [the chametz] is not his. Even if it belonged to a resident alien under the authority of the Jewish people, we need not force him to remove the chametz from his property on Pesach.
Nevertheless, it is necessary to construct a partition at least ten handbreadths high in front of chametz belonging to a gentile, lest one come to use it. [With regard to chametz] that has been consecrated, this is unnecessary; everyone shies away from consecrated property, lest they infringe on [the prohibition of] מעילה.
בהָא לָמַדְתָּ שֶׁהֶחָמֵץ שֶׁל יִשְׂרָאֵל אִם הֱנִיחוֹ בִּרְשׁוּתוֹ אֲפִלּוּ טָמוּן וַאֲפִלּוּ בְּעִיר אַחֶרֶת וַאֲפִלּוּ מֻפְקָד בְּיַד עַכּוּ''ם הֲרֵי זֶה עוֹבֵר מִשּׁוּם (שמות יג ז) (דברים טז ד) "לֹא יֵרָאֶה" וְ(שמות יב יט) "לֹא יִמָּצֵא". חָמֵץ שֶׁל הֶקְדֵּשׁ אוֹ שֶׁל עַכּוּ''ם שֶׁהָיָה אֵצֶל יִשְׂרָאֵל אֲפִלּוּ הָיָה עִמּוֹ בַּבַּיִת הֲרֵי זֶה מֻתָּר מִפְּנֵי שֶׁאֵינוֹ שֶׁלּוֹ. וַאֲפִלּוּ הָיָה שֶׁל גֵּר תּוֹשָׁב שֶׁיַּד יִשְׂרָאֵל שׁוֹלֶטֶת עָלָיו אֵין כּוֹפִין אוֹתוֹ לְהוֹצִיא הֶחָמֵץ מֵרְשׁוּתוֹ בְּפֶסַח. אֲבָל צָרִיךְ לַעֲשׂוֹת מְחִצָּה גְּבוֹהָה עֲשָׂרָה טְפָחִים בִּפְנֵי חֲמֵצוֹ שֶׁל עַכּוּ''ם שֶׁמָּא יָבוֹא לְהִסְתַּפֵּק מִמֶּנּוּ. אֲבָל שֶׁל הֶקְדֵּשׁ אֵינוֹ צָרִיךְ מִפְּנֵי שֶׁהַכּל פּוֹרְשִׁין מִן הַהֶקְדֵּשׁ כְּדֵי שֶׁלֹּא יָבוֹאוּ לִידֵי מְעִילָה:
A gentile who entrusted his chametz to a Jew: Should the Jew accept the responsibility of paying for the worth of the chametz if it is lost or stolen—behold, he is obligated to destroy it. Since he accepted responsibility for it, it is considered as though it were his.
If he did not accept responsibility for it, he may keep it in his domain and may eat from it after Pesach, for it was in the gentile's possession.
געַכּוּ''ם שֶׁהִפְקִיד חֲמֵצוֹ אֵצֶל יִשְׂרָאֵל אִם קִבֵּל עָלָיו יִשְׂרָאֵל אַחֲרָיוּת שֶׁאִם אָבַד אוֹ נִגְנַב יְשַׁלֵּם לוֹ דָּמָיו הֲרֵי זֶה חַיָּב לְבָעֲרוֹ הוֹאִיל וְקִבֵּל עָלָיו אַחֲרָיוּת נַעֲשָׂה כְּשֶׁלּוֹ. וְאִם לֹא קִבֵּל עָלָיו אַחֲרָיוּת מֻתָּר לְקַיְּמוֹ אֶצְלוֹ וּמֻתָּר לֶאֱכל מִמֶּנּוּ אַחַר הַפֶּסַח שֶׁבִּרְשׁוּת הָעַכּוּ''ם הוּא:
Should a gentile who forces his way upon people entrust his chametz to a Jew: If the Jew knows that if it is lost or stolen, [the gentile] will obligate him to pay for it—forcing and compelling him to pay even though he did not accept responsibility—he is obligated to destroy it. It is considered as though it were his, for the gentile holds him responsible for it.
דעַכּוּ''ם אַנָּס שֶׁהִפְקִיד חֲמֵצוֹ אֵצֶל יִשְׂרָאֵל אִם יוֹדֵעַ הַיִּשְׂרָאֵל שֶׁאִם אָבַד אוֹ נִגְנַב מְחַיְּבוֹ לְשַׁלְּמוֹ וְכוֹפֵהוּ וְאוֹנְסוֹ לְשַׁלֵּם אַף עַל פִּי שֶׁלֹּא קִבֵּל אַחֲרָיוּת הֲרֵי זֶה חַיָּב לְבַעֲרוֹ. שֶׁהֲרֵי נֶחְשָׁב כְּאִלּוּ הוּא שֶׁלּוֹ מִפְּנֵי שֶׁמְּחַיְּבוֹ הָאַנָּס בְּאַחְרָיוּתוֹ:
A Jew who gives his chametz to a gentile as security for a loan and tells him: "If I do not bring the money between today and such and such a date, you acquire the chametz [retroactively] from the present moment," the chametz is considered as in the gentile's possession and is permitted to be used after Pesach. This applies if the date specified was before Pesach.
However, if he did not tell him: "you acquire the chametz [retroactively] from the present moment," that chametz is considered as an article entrusted to the gentile, and it is forbidden to benefit from it after Pesach.
היִשְׂרָאֵל שֶׁהִרְהִין חֲמֵצוֹ אֵצֶל הָעַכּוּ''ם אִם אָמַר לוֹ אִם לֹא הֵבֵאתִי לְךָ מָעוֹת מִכָּאן וְעַד יוֹם פְּלוֹנִי קְנֵה חָמֵץ זֶה מֵעַכְשָׁו הֲרֵי זֶה בִּרְשׁוּת הָעַכּוּ''ם וְאוֹתוֹ הֶחָמֵץ מֻתָּר לְאַחַר הַפֶּסַח. וְהוּא שֶׁיִּהְיֶה אוֹתוֹ זְמַן שֶׁקָּבַע לוֹ קֹדֶם הַפֶּסַח. וְאִם לֹא אָמַר לוֹ קְנֵה מֵעַכְשָׁו נִמְצָא אוֹתוֹ הֶחָמֵץ כְּאִלּוּ הוּא פִּקָּדוֹן אֵצֶל הָעַכּוּ''ם וְאָסוּר בַּהֲנָיָה לְאַחַר הַפֶּסַח:
Mishneh Torah (Moznaim)
Featuring a modern English translation and a commentary that presents a digest of the centuries of Torah scholarship which have been devoted to the study of the Mishneh Torah by Maimonides.
A Jew and a gentile are traveling together in a ship, and the Jew possesses chametz. When the fifth hour [on the fourteenth of Nisan] arrives—behold, he should sell it to the gentile or give it to him as a present. He may return and buy it back from him after Pesach, as long as he gives it to him as an outright present.
ויִשְׂרָאֵל וְעַכּוּ''ם שֶׁהָיוּ בָּאִין בִּסְפִינָה וְהָיָה חָמֵץ בְּיַד יִשְׂרָאֵל וְהִגִּיעָה שָׁעָה חֲמִישִׁית הֲרֵי זֶה מוֹכְרוֹ לְעַכּוּ''ם אוֹ נוֹתְנוֹ לוֹ בְּמַתָּנָה וְחוֹזֵר וְלוֹקְחוֹ מִמֶּנּוּ אַחַר הַפֶּסַח. וּבִלְבַד שֶׁיִּתְּנֶנּוּ לוֹ מַתָּנָה גְּמוּרָה:
The Jew may tell the gentile: "Rather than buy a manah's worth [of chametz], come and buy two hundred [dinars'] worth [of chametz]... Rather than buy from a gentile, come and buy from a Jew. Perhaps I will need [chametz] and will buy from you after Pesach."
However, he cannot sell or give [chametz] to him on condition. If he does so—behold, he transgresses [the prohibitions]: "[leaven] shall not be seen" and "[leaven] shall not be found."
זאוֹמֵר יִשְׂרָאֵל לְעַכּוּ''ם עַד שֶׁאַתָּה לוֹקֵחַ בְּמָנֶה בּוֹא וְקַח בְּמָאתַיִם. עַד שֶׁאַתָּה לוֹקֵחַ מֵעַכּוּ''ם בּוֹא וְקַח מִיִּשְׂרָאֵל שֶׁמָּא אֶצְטָרֵךְ וְאֶקַּח מִמְּךָ אַחַר הַפֶּסַח. אֲבָל לֹא יִמְכֹּר וְלֹא יִתֵּן לוֹ עַל תְּנַאי. וְאִם עָשָׂה כֵּן הֲרֵי זֶה עוֹבֵר עַל בַּל יֵרָאֶה וּבַל יִמָּצֵא:
[A person] who possesses a mixture of chametz transgresses [the prohibitions]: "[leaven] shall not be seen" and "[leaven] shall not be found" because of it; for example: pickle-brine, Babylonian kotach, and Median beer, which are made from flour.
[The same applies] to other similar substances which are eaten. However, a substance which contains a mixture of chametz, but is not fit to be eaten, may be kept on Pesach.
חתַּעֲרֹבֶת חָמֵץ עוֹבְרִין עָלֶיהָ מִשּׁוּם בַּל יֵרָאֶה וּבַל יִמָּצֵא. כְּגוֹן הַמּוּרְיָס וְכוּתָח הַבַּבְלִי וְשֵׁכָר הַמָּדִי שֶׁעוֹשִׂין אוֹתוֹ מִן הַקֶּמַח. וְכָל כַּיּוֹצֵא בָּאֵלּוּ מִדְּבָרִים הַנֶּאֱכָלִים. אֲבָל דָּבָר שֶׁיֵּשׁ בּוֹ תַּעֲרֹבֶת חָמֵץ וְאֵינוֹ רָאוּי לַאֲכִילָה הֲרֵי זֶה מֻתָּר לְקַיְּמוֹ בְּפֶסַח:
How is [the latter principle] applied? A tanner's trough into which one placed flour and animal hides: Even if this was done one hour before [the time chametz must be] destroyed, one may keep it. If one placed flour [in the trough] without animal hides three days before [the time chametz must be] destroyed, one may keep it, for the [chametz] has surely become spoiled and rotten. Within three days, one is obligated to destroy it.
טכֵּיצַד. עֲרֵבַת הָעַבְּדָנִין שֶׁנָּתַן לְתוֹכָהּ קֶמַח וְעוֹרוֹת אֲפִלּוּ נְתָנוֹ שָׁעָה אַחַת קֹדֶם הַבִּעוּר הֲרֵי זֶה מֻתָּר לְקַיְּמוֹ. וְאִם לֹא נָתַן הָעוֹרוֹת וְנָתַן הַקֶּמַח קֹדֶם שְׁלֹשָׁה יָמִים לִשְׁעַת הַבִּעוּר מֻתָּר לְקַיְּמוֹ שֶׁהֲרֵי נִפְסַד וְהִבְאִישׁ. תּוֹךְ שְׁלֹשָׁה יָמִים חַיָּב לְבָעֵר:
Similarly, an eye salve, a compress, a plaster, or Tiriac into which chametz was placed may be kept on Pesach, for the nature of the chametz is spoiled.
יוְכֵן הַקִּילוֹר וְהָרְטִיָּה וְהָאִסְפְּלָנִית וְהַתְּרִיאַ''ק שֶׁנָּתַן לְתוֹכָן חָמֵץ מֻתָּר לְקַיְּמָן בְּפֶסַח שֶׁהֲרֵי נִפְסְדָה צוּרַת הֶחָמֵץ:
Bread itself which has become moldy and is no longer fit for consumption by a dog, or a compress that has become spoiled, need not be destroyed.
Clothes which were washed with starch and, similarly, papers which were stuck together with chametz, and other like cases, may be kept on Pesach. Their [possession] does not constitute a [violation of the prohibitions]: "[leaven] shall not be seen" and "[leaven] shall not be found," for they no longer have the form of chametz.
יאהַפַּת עַצְמָהּ שֶׁעִפְּשָׁה וְנִפְסְלָה מִלֶּאֱכל הַכֶּלֶב ומְלוּגְמָא שֶׁנִּסְרְחָה אֵינוֹ צָרִיךְ לְבָעֵר. בְּגָדִים שֶׁכִּבְּסוּ אוֹתָן בְּחֵלֶב חִטָּה וְכֵן נְיָרוֹת שֶׁדִּבְּקוּ אוֹתָן בְּחָמֵץ וְכָל כַּיּוֹצֵא בָּזֶה מֻתָּר לְקַיְּמָן בְּפֶסַח וְאֵין בָּהֶן מִשּׁוּם (שמות יג ז) (דברים טז ד) "לֹא יֵרָאֶה" וְ(שמות יב יט) "לֹא יִמָּצֵא" שֶׁאֵין צוּרַת הֶחָמֵץ עוֹמֶדֶת:
A substance which is not eaten by people, or one which is generally not eaten by people, with which chametz has become mixed— e.g., Tiriac and the like, though one may keep it [during Pesach], eating it is prohibited until after Pesach. Even though it contains only the smallest amount of chametz, eating it is forbidden.
יבדָּבָר שֶׁנִּתְעָרֵב בּוֹ חָמֵץ וְאֵינוֹ מַאֲכָל לְאָדָם כְּלָל. אוֹ שֶׁאֵינוֹ מַאֲכַל כָּל אָדָם כְּגוֹן הַתְּרִיאַ''ק וְכַיּוֹצֵא בּוֹ אַף עַל פִּי שֶׁמֻּתָּר לְקַיְּמוֹ אָסוּר לְאָכְלוֹ עַד אַחַר הַפֶּסַח. וְאַף עַל פִּי שֶׁאֵין בּוֹ מִן הֶחָמֵץ אֶלָּא כָּל שֶׁהוּא הֲרֵי זֶה אָסוּר לְאָכְלוֹ: