Leviticus 16:3-4

“Thus Aaron shall come into the Holy Place: with the blood of a young bull as a sin offering, and of a ram as a burnt offering. He shall put the holy linen tunic and the linen trousers on his body; he shall be girded with a linen sash, and with the linen turban he shall be attired. These are holy garments. Therefore he shall wash his body in water, and put them on.