Positive commandment · Mitzvat Aseh #43 of 613
To offer an additional sacrifice on Pesach
להוסיף קרבן בחג הפסח
The verse · Vayikra 23:36
שִׁבְעַת יָמִים תַּקְרִיבוּ אִשֶּׁה לַה׳ בַּיּוֹם הַשְּׁמִינִי מִקְרָא־קֹדֶשׁ יִהְיֶה לָכֶם וְהִקְרַבְתֶּם אִשֶּׁה לַה׳ עֲצֶרֶת הִוא כׇּל־מְלֶאכֶת עֲבֹדָה לֹא תַעֲשׂוּ
“Seven days you shall offer an offering made by fire to the Lord: on the eighth day shall be a holy gathering to you; and you shall offer an offering made by fire to the Lord; it is a solemn assembly; and you shall do no servile work.”
The Rambam’s words
To offer an additional sacrifice on Pesach, as [Leviticus 23:36] states: "For seven days, you will bring a fire offering unto G-d...."
להוסיף קרבן בחג הפסח, שנאמר: "שִׁבְעַת יָמִים תַּקְרִיבוּ אִשֶּׁה לַיי" (ויקרא כג, לו).
Why · Sefer HaChinuch #299
Additional sacrifices all of the seven days of Pesach
“From the roots of the commandment are what you will see at the end of my words. However, I am afraid of drawing close to the Dwelling of G-d, as I know that “anyone who comes close, who comes close” that has not sufficiently sanctified himself “will not see the House and live.””
Who & when
“And [it] is practiced at the time of the [Temple] by the males of the priesthood.”
Where in the Mishneh Torah
Hilchot Daily Offerings and Additional Offerings הלכות תמידים ומוספין