Leviticus 16:2-4

Modern English Version

² The Lord said to Moses: Speak to Aaron your brother so that he does not come at any time into the Holy Place within the veil before the mercy seat, which is on the ark, so that he will not die, for I will appear in the cloud on the mercy seat.

³ Thus Aaron shall come into the Holy Place with a young bull for a sin offering and a ram for a burnt offering. ⁴ He shall put on the holy linen tunic, and he shall have the linen undergarment on his body, and shall be girded with a linen sash, and shall be wearing the linen turban. These are holy garments. Therefore he shall wash his body in water and then put them on.