Yoma, Chapter 3, Mishnah 6. After the Kohen Gadol finished offering the daily tamid sacrifice brought every single day, including the burning of the incense that accompanied that tamid, the Mishnah turns to describe how he changed into the four linen garments unique to Yom Kippur.
The Parvah Chamber:
"Ve'hevi'uhu l'veis haParvah" - they brought the Kohen Gadol to the Parvah Chamber, a room located in the Azarah. In the words of the Mishnah, "it was holy" - it was considered part of the sanctity of the Azarah, and an immersion room, a mikvah, was above it.
"Parsu sadin shel butz beino l'vein ha'am" - once again they spread out a partition made of linen between him and the people who were present in the area, so that he would have privacy.
"Kidesh yadav v'raglav u'fashat" - he sanctified his hands and feet, meaning he washed his hands and feet, and afterward he removed the ordinary golden garments he had been wearing.
Rabbi Meir disagrees with this order. In his view, "pashat" comes first: first he removed the golden garments, and only afterward did he "kidesh yadav v'raglav".
We will explain the root of the dispute below; first let us read the continuation of the Mishnah's words:
"Yarad v'taval" - he went down to the mikvah and immersed.
"Alah v'nistapeg" - he came up and dried himself.
"V'hevi'u lo bigdei lavan" - they brought him the white garments of Yom Kippur.
"Lavash v'kidesh yadav v'raglav" - he put them on, and again sanctified his hands and feet.
What is the purpose of the first sanctification of the hands and feet?
On this question the Tanna Kamma, who holds that he sanctified his hands and feet before removing the golden garments, and Rabbi Meir, who holds that he first removed the garments and only afterward sanctified, disagree:
According to the Tanna Kamma: the first sanctification of the hands and feet is part of the honor he shows to the previous garments he had been wearing, and therefore it is done before he removes them.
According to Rabbi Meir: both sanctifications of the hands and feet - the one before the immersion and the one after putting on the white garments - are both for the honor of the garments he is about to put on. For this reason he sanctifies his hands and feet only after he has removed the previous garments, since the first sanctification has no connection to them at all.
In summary: in this Mishnah we learned the order in which the Kohen Gadol changed his garments after the tamid service: he was brought to the Parvah Chamber in the Azarah, a linen sheet was spread between him and the people, he sanctified his hands and feet, removed the golden garments, immersed, dried himself and put on the white garments, and again sanctified his hands and feet. We also examined the dispute between the Tanna Kamma and Rabbi Meir regarding the placement of the first sanctification, which depends on whether it is done for the honor of the garments being removed or for the honor of the garments about to be put on.