Horayos 3:4 - 3:5

המרובה בגדים – for after the flask of anointing oil was hidden away the Kohen Gadol would enter the High Priesthood through the wearing of eight [sets of] clothing, as it is written (Leviticus 21:10): “…and who has been ordained to wear the vestments…”

אלא פר הבא על כל המצות – the [High Priest] who wears the many dedicated garments does not bring a bullock on his inadvertent sin, as it is written (Leviticus 4:3,5): “the anointed priest.

בעבודת יום הכפורים – for the Divine service of that day is not fit other than through the High Priest alone. But the presently serving Kohen and one who served in the past are equivalent concerning these things.

ולא פורעין ולא פרומין – as it is written concerning the High Priest (Leviticus 21:10): “[he] shall not bare his head or rend his vestments.”

ומחזירין את הרוצח – if one of these dies, the killer returns from his city of refuge, as it is written (Numbers 35:28): “[For he must remain inside his city of refuge] until the death of the high priest…”

כהן גדול פורם מלמטה – If he sustained a death where he is obligated to tear [his clothing], he tears from the bottom at the corner of his garment nearest his feet. And this [verse] that is written (Leviticus 21:10): “or rend his vestments,” for he does not rend like other people.

מלמעלה – opposite/corresponding to the breast near the shoulder, like other people.

אונן – he who sustained a death from one of the seven relatives that he (i.e., a Kohen) is obligated to mourn for, the entire day of death, whether the deceased is buried whether it is not buried [that day], he is an Onan/mourner before the funeral of a kinsman according to the Torah, and from the day of death and onwards, all the while that the deceased is not buried, he is an Onan according to the Rabbis, but the day of burial he is an Onan according to the Rabbis all that day, even after the burial, and from when the deceased is buried on the first day of death, all that night afterwards, he is an Onan according to the Rabbis.

כהן גדול מקריב אונן ולא אוכל – from the Holy Things, for such we found with Aaron on the day that Nadav and Avihu died, he said (Leviticus 10:19): “Had I eaten purification offering today, would the LORD have approved?” On the eating he was stringent but not n the bringing of the offering. And specifically, Aaron who was the High Priest, but his sons who were common priests, they were forbidden that entire day whether to offer [a sacrifice] or to eat from it.