שֶׁלֹּא נַאֲכִיל מִן הַפֶּסַח לְיִשְׂרָאֵל מְשֻׁמָּד – שֶׁלֹּא נַאֲכִיל מִן הַפֶּסַח לְיִשְׂרָאֵל מוּמָר לַעֲבוֹדָה זָרָה, שֶׁנֶּאֱמַר: (שמות יב מג) כָּל בֶּן נֵכָר לֹא יֹאכַל בּוֹ, וּבָא הַפֵּרוּשׁ עָלָיו, (מכילתא שם) בֶּן יִשְׂרָאֵל שֶׁנִּתְנַכְּרוּ מַעֲשָׂיו לְאָבִיו שֶׁבַּשָּׁמַיִם, וְכֵן תִּרְגֵּם אוּנְקְלוֹס. That we not feed of the Pesach sacrifice to an apostate Jew: That we not feed of (allow to eat from) the Pesach sacrifice to a Jew that is a habitual sinner of idolatry, as it is stated (Exodus 12:43), “no foreigner shall eat of it.” And the understanding (Mekhilta DeRabbi Shimon Bar Yochai 12:43) comes upon it that [this “foreigner”] is a Jew whose actions have become foreign to his Father in Heaven. And so did Onkelos translate.
מִשָּׁרְשֵׁי מִצְוָה זוֹ, כְּמוֹ שֶׁכָּתוּב בִּשְׁחִיטָתוֹ, לְזֵכֶר נִסֵּי מִצְרַיִם, וְעַל כֵּן רָאוּי שֶׁלֹּא יֹאכַל בּוֹ מוּמָר (מְשֻׁמָּד), מֵאַחַר שֶׁאָנוּ עוֹשִׂין אוֹתוֹ לְאוֹת וּלְזִכָּרוֹן שֶׁבָּאנוּ בְּאוֹתוֹ הַזְּמַן לַחֲסוֹת תַּחַת כַּנְפֵי הַשְּׁכִינָה וְנִכְנַסְנוּ בִּבְרִית הַתּוֹרָה וְהָאֱמוּנָה, אֵין רָאוּי שֶׁנַּאֲכִיל מִמֶּנּוּ לְמִי שֶׁהוּא הֵפֶךְ מִזֶּה שֶׁיָּצָא מִן הַכְּלָל וְכָפַר בָּאֱמוּנָה. וְעַל כַּיּוֹצֵא בָּזֶה נֶאֱמַר בַּגְּמָרָא לִפְעָמִים: סְבָרָא הוּא, כְּלוֹמַר וְאֵין צָרִיךְ רְאָיָה אַחֶרֶת (פ"ט מהלכות קרבן פסח) From the roots of this commandment is like that which is written about its slaughter (Sefer HaChinukh 5) — that it is to remember the miracles of Egypt. And therefore it is fitting that a habitual sinner (apostate) not eat from it. Since we are doing it as a sign and as a memory device that we came at that time to take refuge under the wings of the Divine Presence and that we entered into the covenant of Torah and faith, it is not fitting that we feed him — someone who is the opposite of this and went out from the group and denied the faith — of it. And sometimes it is said in the Gemara about things similar to this, “It is logical” — meaning to say that there is no need for a [further] proof (Mishneh Torah, Laws of Paschal Offering 9).
וְנוֹהֶגֶת בִּזְכָרִים וּנְקֵבוֹת בִּזְמַן הַבַּיִת שֶׁיֵּשׁ שָׁם פֶּסַח. וְעוֹבֵר עָלֶיהָ וְהֶאֱכִיל מִמֶּנּוּ לְבֶן נֵכָר עוֹבֵר עַל לָאו. וְאֵין בּוֹ מַלְקוּת לְפִי שֶׁאֵין בּוֹ מַעֲשֶׂה. (רמב"ם שם ה"ז). And [it] is practiced by males and females at the time of the [Temple], where there is a Pesach sacrifice. And the one who transgresses it and feeds a “foreigner” from it violates this negative commandment. And there are no lashes for it, since there is no act [involved] with it (Mishneh Torah, Laws of Paschal Offering 9:7).