Midrash su Levitico 16:23

2) (Vayikra 16:23) ("Then Aaron shall come to the tent of meeting, and he shall take off the linen garments which he put on when he went into the holy place, and he shall leave them there.") "Then Aaron shall come to the tent of meeting": The entire section is stated according to the order (of the service of the high-priest) except for this verse. And why did he come there? To remove the incense ladle and the coal pan.

3) R. Yehudah said: Whence are derived the five immersions and the ten lustrations (washing of hands and feet) that the high-priest performs on that day? From (Vayikra 16:23) "Then Aaron shall come to the tent of meeting, and he shall take off the linen garments which he put on when he went into the holy place … (Vayikra 16:24) And he shall bathe his flesh in water in a holy place, and he shall put on his (eight everyday) garments." From here we derive that all transitions from one service to another requires immersion — whence we derive that he performed five immersions and ten lustrations on that day.

4) Rebbi says: Do I derive it from there? Is it not already written (Vayikra 16:4) "And he shall bathe his flesh in water and he shall put them on," and (Vayikra 16:4) "they are holy garments"? All the garments are likened to each other, to teach that changing from golden vestments to white vestments and from white vestments to golden vestments requires immersion (and since there are five changings, there are five immersions and ten lustrations for each doffing and donning).