Ezekiel 44:17

¹⁷ And it shall come to pass, that when they enter in at the gates of the inner court, they shall be clothed with linen garments; and no wool shall come upon them, whiles they minister in the gates of the inner court, and within.

Shave the head

'To shave the head' was strictly prohibited for the high-priests and his sons because of the holy representation of hair and of the Nazarite.