Mishnah 1א׳
מִי שֶׁהָיָה טָמֵא אוֹ בְדֶרֶךְ רְחוֹקָה וְלֹא עָשָׂה אֶת הָרִאשׁוֹן, יַעֲשֶׂה אֶת הַשֵּׁנִי. שָׁגַג אוֹ נֶאֱנַס וְלֹא עָשָׂה אֶת הָרִאשׁוֹן, יַעֲשֶׂה אֶת הַשֵּׁנִי. אִם כֵּן, לָמָּה נֶאֱמַר טָמֵא אוֹ שֶׁהָיָה בְדֶרֶךְ רְחוֹקָה, שֶׁאֵלּוּ פְּטוּרִין מֵהִכָּרֵת, וְאֵלּוּ חַיָּבִין בְּהִכָּרֵת:
If one were unclean or on a distant way, and he did not offer the first Pesach, he offers the second. If unwittingly or under constraint he did not offer the first Pesach, he offers the second. If so, why is it written (Numbers 9:10): "…if he were unclean or on a distant way"? For these are exempt from kareth and the others are liable for kareth. [Scripture exempts one who was unclean or on a distant way from offering the first Pesach, and kareth, essentially, is for the first Pesach. Therefore, if they did not offer the second Pesach, they are exempt from kareth. But if one were unwitting or under constraint, he was (in principle) obligated to offer the first Pesach; it is just that his particular condition prevented him from doing so. So that if he wittingly does not offer the second Pesach, he is liable for kareth, viz. (Ibid. 13): "And the man who is clean and was not on the way and who failed to offer the Pesach, that soul shall be cut off," the implication being that for all other varieties of unwittingness or constraint which may have obtained vis-à-vis the first Pesach, aside from uncleanliness and being on a distant way, there is kareth liability for failure to offer the second Pesach.]
Mishnah 2ב׳
אֵיזוֹ הִיא דֶרֶךְ רְחוֹקָה, מִן הַמּוֹדִיעִים וְלַחוּץ, וּכְמִדָּתָהּ לְכָל רוּחַ, דִּבְרֵי רַבִּי עֲקִיבָא. רַבִּי אֱלִיעֶזֶר אוֹמֵר, מֵאַסְקֻפַּת הָעֲזָרָה וְלַחוּץ. אָמַר רַבִּי יוֹסֵי, לְפִיכָךְ נָקוּד עַל ה', לוֹמַר, לֹא מִפְּנֵי שֶׁרְחוֹקָה וַדַּאי, אֶלָּא מֵאִסְקֻפַּת הָעֲזָרָה וְלַחוּץ:
Which is a "distant way"? From Modi'im and beyond. [Modi'im was fifteen mils from Jerusalem, the distance an average man can walk in the days of Nissan and the days of Tishrei, when the days and nights are equal, from sunrise until ben ha'arbayim (towards evening), which is the time for the offering of the sacrifice.] R. Eliezer says: From the threshold of the azarah (the Temple court) and beyond. [Even if he were close to Jerusalem and took ill and was delayed and did not arrive at the threshold of the azarah until the end of the time for the offering of the Pesach, he comes under the law of a "distant way." And R. Akiva holds that he comes under the law of one who was constrained, but not under the law of a "distant way."] R. Yossi said: That is why there is a point above the heh [in "rechokah" ("distant")], to connote not "distant," literally, but from the threshold of the azarah and beyond. [I have heard it expounded thus: "five ('heh' = five) cubits from the threshold of the azarah," i.e., even if he were only five cubits distant at the end of the time of the Pesach offering, he comes under a "distant way."]
Mishnah 3ג׳
מַה בֵּין פֶּסַח רִאשׁוֹן לַשֵּׁנִי, הָרִאשׁוֹן אָסוּר בְּבַל יֵרָאֶה וּבַל יִמָּצֵא, וְהַשֵּׁנִי, מַצָּה וְחָמֵץ עִמּוֹ בַּבָּיִת. הָרִאשׁוֹן טָעוּן הַלֵּל בַּאֲכִילָתוֹ, וְהַשֵּׁנִי אֵינוֹ טָעוּן הַלֵּל בַּאֲכִילָתוֹ. זֶה וָזֶה טָעוּן הַלֵּל בַּעֲשִׂיָּתָן, וְנֶאֶכָלִין צָלִי עַל מַצּוֹת וּמְרוֹרִים, וְדוֹחִין אֶת הַשַּׁבָּת:
What is the difference between the first and the second Pesach? With the first, bal yeraeh and bal yimatzeh obtain; with the second, matzah and chametz are together with him in the house. [For it is written (Numbers 9:12): "according to all the statute of the (first) Pesach shall they offer it" (the second Pesach). The implication is that vis-à-vis (direct) mitzvoth of its body, such as roasting it and eating it together with matzoth and maror, it is offered according to all of the statute of the (first) Pesach. But with extraneous mitzvoth related to its body, such as the removal of se'or (from one's house) and not slaughtering it in the presence of chametz, it is not offered according to all of the statute of the first Pesach.] The first requires Hallel at its eating; the second does not require Hallel at its eating. [For it is written (Isaiah 30:29): "Then you shall have song, as in the night consecrated as a festival," i.e., the first Pesach. And what is not consecrated as a festival does not require Hallel.] Both require Hallel at their offering, [the (above) verse having excluded "night" from song (for the second Pesach), and not day.] And they are both eaten roasted, together with matzah and maror, and they override the Sabbath.
Mishnah 4ד׳
הַפֶּסַח שֶׁבָּא בְטֻמְאָה, לֹא יֹאכְלוּ מִמֶּנּוּ זָבִין וְזָבוֹת נִדּוֹת וְיוֹלְדוֹת. וְאִם אָכְלוּ, פְּטוּרִים מִכָּרֵת. רַבִּי אֱלִיעֶזֶר פּוֹטֵר אַף עַל בִּיאַת מִקְדָּשׁ:
A Pesach brought in uncleanliness may not be eaten by zavin and zavoth, niddoth, and yoldoth (women who have just given birth). [For in respect to (Exodus 9:10): "…if he become unclean by a body," it is written: "a man," which is expounded: A man is pushed off (to Pesach sheni), but a congregation is not pushed off. But with zivah (and related) uncleanliness, even a congregation is pushed off.]; but if they do eat, they are exempt from kareth. [For in respect to the eating of kodshim in uncleanliness of body it is written (Leviticus 7:19): "Everyone that is clean may eat flesh," followed by (Ibid. 20): "And the soul that eats flesh … and his uncleanliness is upon him, that soul shall be cut off from its people" — Flesh which is eaten by the clean, if the unclean eat it, they are liable (to kareth) for uncleanliness; flesh which is not eaten by the clean, e.g., a Pesach which is brought in uncleanliness, if the unclean eat it they are not liable (to kareth) for uncleanliness.] R. Eliezer exempts [zavin and zavoth from kareth] even for entering the sanctuary. [If they entered the sanctuary, they are exempt when the Pesach is overridden by uncleanliness (i.e., when it may be eaten in uncleanliness), viz. (Numbers 5:2): "And let them send out of the camp every leper and every zav and everyone that is unclean by a body" — When those unclean by a body are sent out, zavin and lepers are sent out; when those unclean by a body are not sent out, zavin and lepers are not sent out. And the first tanna does not expound the verse thus, for all must be separated from their (respective) encampments. The halachah is not in accordance with R. Eliezer.]