Reference for Pesachim 8:8
אוֹנֵן טוֹבֵל וְאוֹכֵל אֶת פִּסְחוֹ לָעֶרֶב, אֲבָל לֹא בַקָּדָשִׁים. הַשּׁוֹמֵעַ עַל מֵתוֹ, וְהַמְלַקֵּט לוֹ עֲצָמוֹת, טוֹבֵל וְאוֹכֵל בַּקָּדָשִׁים. גֵּר שֶׁנִּתְגַּיֵּר בְּעֶרֶב פֶּסַח, בֵּית שַׁמַּאי אוֹמְרִים, טוֹבֵל וְאוֹכֵל אֶת פִּסְחוֹ לָעֶרֶב. וּבֵית הִלֵּל אוֹמְרִים, הַפּוֹרֵשׁ מִן הָעָרְלָה כְּפוֹרֵשׁ מִן הַקָּבֶר:
An onan immerses and eats his Pesach at night, [Torah aninuth (mourning) obtaining only in the daytime, viz. (Leviticus 10:19): "…and if I had eaten a sin-offering this day, etc." — the day is forbidden; the night is permitted. And he requires immersion: Because kodshim had been forbidden to him until now, the rabbis required that he immerse. But an onan may not eat other kodshim (aside from Pesach) at night, for night-aninuth is forbidden (in kodshim) by rabbinic ordinance. But vis-à-vis Pesach, the rabbis did not establish their words in the face of kareth.], but not (other) kodshim, [for the eating of other kodshim is only an aseh (a positive commandment), viz. (Exodus 29:33): "And they shall eat those things with which atonement was made."] If one hears about his dead one (i.e., that one of his close kin has died), [(On the day of his hearing, he is an onan derabanan)], and, [likewise], if one gathers the bones [of his father or mother (— it is stated in Moed Katan that he mourns them the entire day and does not mourn them at night)], he immerses and eats kodshim at night, [for in the daytime itself, he is only an onan derabanan]. If one becomes a proselyte on Pesach eve, Beth Shammai say: He immerses and eats his Pesach at night. Beth Hillel say: One who separates from the foreskin is as one who separates from the grave, [and he requires sprinkling on the third and seventh days. Beth Shammai and Beth Hillel differ only in respect to an uncircumcised gentile, who circumcised himself on the fourteenth (of Nissan), Beth Hillel holding — a decree, lest he become unclean the next year and say: "Last year I was not cleaned of all my uncleanliness until the day of Pesach eve, when I immersed and ate — now, too, I will immerse and eat" — not realizing that the preceding year, having been a gentile, he had not acquired uncleanliness, and that now, being a Jew, he does acquire uncleanliness. And Beth Shammai hold that we do not decree thus. But in respect to an uncircumcised Jew (as when his brothers died because of circumcision), all agree that he immerses and eats his Pesach at night, and we do not decree "an uncircumcised Jew by reason of an uncircumcised gentile."]