That we not slaughter the lamb of the Pesach-offering on the fourteenth of Nissan while chamets is still in our possession: That we not slaughter the lamb of the Pesach offering on the fourteenth of Nissan while chamets still be in our possession — until half of the day, as they, may their memory be blessed, expounded (Pesachim 5a),”[The word,] ‘but,’ divides” — as it is stated (Exodus 23:18), “Do not slaughter upon chamets the blood of My slaughtering.” And the explanation of it comes [to tell us] not to slaughter the lamb of the Pesach sacrifice while chamets still exist in your possession. And this preventing is repeated in the Torah, with a different expression. And we have also understood that included in the explanation is that chamets not be with the one who slaughters it (Pesachim 13b) and not be with the one that sprinkles its blood and not be with the one that makes its fat smoke and not be with one of the assemblage that is counted upon it (Pesachim 63b).
It is from the roots of the commandment [that it is] because it is something known to every man that setting the time for all matters is the preservation of their doing. And so with the matter of Pesach — which is a big thing for us in preserving the religion, as we have written above (Sefer HaChinukh 21) — God, blessed be He, commanded that we do its content in order, and in set times for each and every part of its things; and that no commandment from the matter of the commandments of this time period come into the boundary of its fellow. And therefore, we were warned to first dispose of the chamets — which is disgusting in our eyes — at its time; and afterwards to begin with the Pesach sacrifice, which is the beginning of the good time period. But also if we hear better than this, we will hold from it.
From the laws of the commandment — that which they said (Pesachim 61a), that the time of its slaughter is after midday and that if it is slaughtered before midday it is disqualified; that even though its time is after midday, it is ideally not slaughtered until after the daily afternoon sacrifice, after they burnt the incense of the afternoon, [and] also after [a priest] has prepared the lights [of the menorah]; and the rest of its details — are in Pesachim. (See Mishneh Torah, Laws of Paschal Offering 1.)
And [it] is practiced in the time of the Temple by males and by females. And one who transgresses it and consciously leaves a kazayit of chamets in his possession at the time of its sacrifice — whether he sacrifices it or sprinkles [its blood] or burns the portions to be burnt or even [if he is] one from all of those counted in the assemblage for its eating — is lashed. But the Pesach sacrifice is fit nonetheless.
שֶׁלֹּא נִשְׁחַט שֵׂה הַפֶּסַח בְּאַרְבָּעָה עָשָׂר בְּנִיסָן בְּעוֹד הֶחָמֵץ בִּרְשׁוּתֵנוּ – שֶׁלֹּא נִשְׁחַט שֵׂה הַפֶּסַח בְּאַרְבָּעָה עָשָׂר בְּנִיסָן בְּעוֹד שֶׁיִּהְיֶה חָמֵץ בִּרְשׁוּתֵנוּ עַד חֲצִי הַיּוֹם, כְּמוֹ שֶׁדָּרְשׁוּ זִכְרוֹנָם לִבְרָכָה (פסחים ה א) אַךְ חִלֵּק, שֶׁנֶּאֱמַר (שמות כג יח) לֹא תִזְבַּח עַל חָמֵץ דַּם זִבְחִי, וּבָא הַפֵּרוּשׁ בּוֹ לֹא תִּשְׁחַט שֶׂה הַפֶּסַח וְיִהְיֶה עֲדַיִן חָמֵץ קַיָּם בִּרְשׁוּתְךָ. וְנִכְפְּלָה זֹאת הַמְּנִיעָה בְּלָשׁוֹן אַחֵר בַּתּוֹרָה. וְגַם כֵּן שָׁמַעְנוּ בִּכְלָל הַפֵּרוּשׁ, שֶׁלֹּא (שם יג ב) יִהְיֶה חָמֵץ אֵצֶל הַשּׁוֹחֵט אוֹתוֹ וְלֹא אֵצֶל הַזּוֹרֵק דָּמוֹ וְלֹא אֵצֶל הַמַּקְטִיר חֶלְבּוֹ וְלֹא אֵצֶל אֶחָד מִבְּנֵי חֲבוּרָה הַנִּמְנִין עָלָיו (שם סג ב).
That we not slaughter the lamb of the Pesach-offering on the fourteenth of Nissan while chamets is still in our possession: That we not slaughter the lamb of the Pesach offering on the fourteenth of Nissan while chamets still be in our possession — until half of the day, as they, may their memory be blessed, expounded (Pesachim 5a),”[The word,] ‘but,’ divides” — as it is stated (Exodus 23:18), “Do not slaughter upon chamets the blood of My slaughtering.” And the explanation of it comes [to tell us] not to slaughter the lamb of the Pesach sacrifice while chamets still exist in your possession. And this preventing is repeated in the Torah, with a different expression. And we have also understood that included in the explanation is that chamets not be with the one who slaughters it (Pesachim 13b) and not be with the one that sprinkles its blood and not be with the one that makes its fat smoke and not be with one of the assemblage that is counted upon it (Pesachim 63b).
מִשָּׁרְשֵׁי הַמִּצְוָה, לְפִי שֶׁקְּבִיעוּת זְמַן בְּכָל הָעִנְיָנִים הוּא קִיּוּם עֲשִׂיָּתָן, יָדוּעַ הַדָּבָר אֵצֶל כָּל אָדָם. וְעַל כֵּן בִּדְבַר הַפֶּסַח, שֶׁהוּא דָּבָר גָּדוֹל אֶצְלֵנוּ בְּקִיּוּם הַדָּת, כְּמוֹ שֶׁכָּתַבְנוּ לְמַעְלָה (במצוה כא), צִוָּה הָאֵל בָּרוּךְ הוּא שֶׁנַּעֲשֶׂה עִנְיָנוֹ בְּסֵדֶר וּבִקְבִיעוּת זְמַן לְכָל דָּבָר וְדָבָר מִדְּבָרָיו, וְלֹא תָּבֹא מִצְוָה מִמִּצְוֹת עִנְיַן הַמּוֹעֵד הַזֶּה בִּגְבוּל חֲבֶרְתָּהּ. וְעַל כֵּן נִזְהַרְנוּ לְהַשְׁבִּית הֶחָמֵץ הַנִּמְאָס בְּעֵינֵינוּ לִשְׁעָתוֹ תְּחִלָּה וְאַחַר כָּךְ לְהַתְחִיל בְּקָרְבַּן הַפֶּסַח שֶׁהוּא הַתְחָלַת שִׂמְחַת הַמּוֹעֵד הַטּוֹב. וְעוֹד אִם שָׁמַעְנוּ טוֹב מִזֶּה נַחְזִיק בּוֹ.
It is from the roots of the commandment [that it is] because it is something known to every man that setting the time for all matters is the preservation of their doing. And so with the matter of Pesach — which is a big thing for us in preserving the religion, as we have written above (Sefer HaChinukh 21) — God, blessed be He, commanded that we do its content in order, and in set times for each and every part of its things; and that no commandment from the matter of the commandments of this time period come into the boundary of its fellow. And therefore, we were warned to first dispose of the chamets — which is disgusting in our eyes — at its time; and afterwards to begin with the Pesach sacrifice, which is the beginning of the good time period. But also if we hear better than this, we will hold from it.
מִדִּינֵי הַמִּצְוָה, מָה שֶׁאָמְרוּ (שם סא א) שֶׁזְּמַן שְׁחִיטָתוֹ אַחַר חֲצוֹת, וְאִם שְׁחָטוֹ קֹדֶם חֲצוֹת שֶׁפָּסוּל, וְאַף עַל פִּי שֶׁאַחַר חֲצוֹת הוּא זְמַנּוֹ, אֵינוֹ נִשְׁחָט לְכַתְּחִלָּה אֶלָּא אַחַר תָּמִיד שֶׁל בֵּין הָעַרְבַּיִם אַחַר שֶׁמַּקְטִירִין קְטֹרֶת שֶׁל בֵּין הָעַרְבַּיִם, גַּם לְאַחַר שֶׁמֵּיטִיב אֶת הַנֵּרוֹת, וְיֶתֶר פְּרָטֶיהָ בִּפְסָחִים [פ"ק מהלכות קרבן פסח]
From the laws of the commandment — that which they said (Pesachim 61a), that the time of its slaughter is after midday and that if it is slaughtered before midday it is disqualified; that even though its time is after midday, it is ideally not slaughtered until after the daily afternoon sacrifice, after they burnt the incense of the afternoon, [and] also after [a priest] has prepared the lights [of the menorah]; and the rest of its details — are in Pesachim. (See Mishneh Torah, Laws of Paschal Offering 1.)
וְנוֹהֶגֶת בִּזְמַן הַבַּיִת בִּזְכָרִים וּבִנְקֵבוֹת. וְהָעוֹבֵר עָלֶיהָ וְהִנִּיחַ מִדַּעְתּוֹ כַּזַּיִת חָמֵץ בִּרְשׁוּתוֹ בִּשְׁעַת הַקְרָבָתוֹ, אֶחָד שׁוֹחֵט אוֹ זוֹרֵק אוֹ מַקְטִיר הָאֵמוּרִין אוֹ אֲפִלּוּ אֶחָד מִכָּל בְּנֵי הַחֲבוּרָה הַנִּמְנִין בַּאֲכִילָתוֹ לוֹקֶה, וְהַפֶּסַח כָּשֵׁר מִכָּל מָקוֹם.
And [it] is practiced in the time of the Temple by males and by females. And one who transgresses it and consciously leaves a kazayit of chamets in his possession at the time of its sacrifice — whether he sacrifices it or sprinkles [its blood] or burns the portions to be burnt or even [if he is] one from all of those counted in the assemblage for its eating — is lashed. But the Pesach sacrifice is fit nonetheless.