יומא א׳Yoma 1

Mishnah 1א׳

שִׁבְעַת יָמִים קֹדֶם יוֹם הַכִּפּוּרִים מַפְרִישִׁין כֹּהֵן גָּדוֹל מִבֵּיתוֹ לְלִשְׁכַּת פַּלְהֶדְרִין, וּמַתְקִינִין לוֹ כֹהֵן אַחֵר תַּחְתָּיו, שֶׁמָּא יֶאֱרַע בּוֹ פְסוּל. רַבִּי יְהוּדָה אוֹמֵר, אַף אִשָּׁה אַחֶרֶת מַתְקִינִין לוֹ, שֶׁמָּא תָמוּת אִשְׁתּוֹ, שֶׁנֶּאֱמַר (ויקרא טז) וְכִפֶּר בַּעֲדוֹ וּבְעַד בֵּיתוֹ. בֵּיתוֹ, זוֹ אִשְׁתּוֹ. אָמְרוּ לוֹ, אִם כֵּן, אֵין לַדָּבָר סוֹף:

Seven days before the Day of Atonement, we sequester the High Priest from his house to the Palhedrin Chamber, and we prepare for him another priest in his place, [for] perhaps there will occur in him a disqualification. Rabbi Yehuda says: We even prepare another wife for him, [for] perhaps his wife will die; as it is said, "and he shall atone for himself and for his household" - his "household" is his wife. The Sages said: If so, there is no end to the matter.

Mishnah 2ב׳

כָּל שִׁבְעַת הַיָּמִים הוּא זוֹרֵק אֶת הַדָּם וּמַקְטִיר אֶת הַקְּטֹרֶת וּמֵטִיב אֶת הַנֵּרוֹת וּמַקְרִיב אֶת הָרֹאשׁ וְאֶת הָרֶגֶל. וּשְׁאָר כָּל הַיָּמִים, אִם רָצָה לְהַקְרִיב, מַקְרִיב, שֶׁכֹּהֵן גָּדוֹל מַקְרִיב חֵלֶק בָּרֹאשׁ וְנוֹטֵל חֵלֶק בָּרֹאשׁ:

All seven days [of his sequestration], [the High Priest] casts the blood, and burns the incense, and cleans the lamps, and offers the head and the leg [of the continual-offering]. All other days, if he wants to offer, he offers — for the High Priest offers a portion first, and takes a portion first.