Leviticus 16:3-4

After this sort shall Aaron come into the Holy place: euen with a yong bullocke for a sinne offring, and a ramme for a burnt offring.

He shall put on the holy linnen coate, and shall haue linnen breeches vpon his flesh, and shall be girded with a linnen girdle, and shall couer his head with a linnen miter: these are the holy garments: therefore shall hee wash his flesh in water, when he doeth put them on.