Leviticus 16:4

The high priest when he changed his dress on this day was required to bathe himself. In his "golden garments" he had, on this day, and for the previous week, to offer the regular daily sacrifices, and to perform the other sacerdotal duties of the sanctuary, which were usually performed by a common priest. The dress of white linen, which he now put on, appears to have been like the ordinary dress of the common priests, except in the substitution of a linen mitre for the bonnet (or cap), and of a plain linen girdle for the variegated one (Exodus 28:40-43 notes). In preparing to enter the holy of holies, he attired himself in spotless white as a token of the holiness without which none, in a spiritual sense, can enter the divine presence. He thus became a more distinct foreshadow of the greater high priest Hebrews 7:26; Hebrews 6:19-20. This significance belonged to the high priest only in his official capacity as mediator: in his own person he had infirmity, and was required "to offer up sacrifice, "first" for his own sins, and then for the people' s." Hebrews 7:27. See the notes at Leviticus 9:7-14. On the same ground it was that, although as a mediator he had to enter the most holy place, as sinful man he needed the cloud of incense as a veil to come between him and the holiness of Yahweh. See Leviticus 16:13.