שֶׁלֹּא לַעֲשׂוֹת שְׁיָרֵי מְנָחוֹת חָמֵץ – שֶׁלֹּא לְבַשֵּׁל שְׁיָרֵי מְנָחוֹת חָמֵץ וְהוּא חֵלֶק הַמְּנָחוֹת אֲשֶׁר לַכֹּהֲנִים, שֶׁנֶּאֱמַר (ויקרא ו י) בְּמִנְחָה לֹא תֵאָפֶה חָמֵץ חֶלְקָם נָתַתִּי אֹתָהּ מֵאִשָּׁי, וְהוּא כְּאִלּוּ אָמַר חֶלְקָם, שֶׁהוּא שְׁיָרֵי הַמִּנְחָה, לֹא יֵאָפֶה חָמֵץ. וּבְפֵרוּשׁ אָמְרוּ זִכְרוֹנָם לִבְרָכָה בַּמִּשְׁנָה (מנחות נה א) וְחַיָּבִים עַל אֲפִיָּתָהּ חָמֵץ. To not make the remainders of the meal-offering chamets (leavened): To not cook the remainders of the meal-offerings [to make them] chamets — and that is the portion of the meal-offerings that is of the priests — as it is stated (Leviticus 6:10), “It shall not be baked chamets, their portion have I given it of My fire-offerings.” And it is as if it said, “Their portion — which is the remainders of the meal-offering — you shall not bake chamets.” And in the explanation, they, may their memory be blessed, said in the Mishnah (Menachot 55a), “And they are liable for its baking [to make it] chamets.”
מִדִּינֵי הַמִּצְוָה. כְּגוֹן מַה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (שם נו א) שֶׁהַמְּחַמֵּץ אַחַר הַמְּחַמֵּץ חַיָּב, וְהַמְּחַמֵּץ (שם נז א) מִנְחָה פְּסוּלָה פָּטוּר, שֶׁנֶּאֱמַר (שם ב יא) אֲשֶׁר תַּקְרִיבוּ לַיְיָ לֹא תֵעָשֶׂה חָמֵץ, הַכְּשֵׁרָה לַשֵּׁם וְלֹא הַפְּסוּלָה. חִמְּצָהּ בְּרֹאשׁ הַמִּזְבֵּחַ אֵינוֹ לוֹקֶה, שֶׁנֶּאֱמַר (שם) אֲשֶׁר תַּקְרִיבוּ לַיְיָ לֹא תֵעָשֶׂה חָמֵץ, וְזוֹ כְּבָר קָרְבָה. וְיֶתֶר פְּרָטֶיהָ מְבֹאָרִים בְּפֶרֶק ה' מִמְּנָחוֹת. From the laws of the commandment is, for example, that which they, may their memory be blessed, said (Menachot 56a) that one who renders it chamets after [another has already] rendered it chamets is liable; and one who renders a disqualified meal-offering chamets is exempt, as it is stated (Leviticus 2:11), “that you shall offer to the Lord, you shall not make chamets” — one that is proper for God and not one that is disqualified. [If] he rendered it chamets on top of the altar, he is not lashed, as it is stated, “that you shall offer to the Lord, you shall not make chamets” — and this one was already offered. And the rest of its details are elucidated in Chapter Five of Menachot.
וְנוֹהֶגֶת מִצְוָה זוֹ בִּזְמַן הַבַּיִת בִּזְכָרִים וּנְקֵבוֹת. אֲפִלּוּ עָבַר יִשְׂרָאֵל אֶחָד וַאֲפָאָהּ חָמֵץ חַיָּב מַלְקוּת, וְאֵין צָרִיךְ לוֹמַר כֹּהֵן. And this commandment is practiced at the time of the [Temple] by males and females. Even an Israelite that transgressed and baked it chamets is liable for lashes, and there is no need to say [that it is so] about a priest.