Leviticus 8:30

Vestments. It is a maxim among the Rabbins, that a priest without his vestments, is not considered as such; and he is put to death, if he should dare to approach the altar in that condition. When the priests lay aside their sacred robes, they are looked upon as laymen. (Calmet) --- The high priest was consecrated by the unction on the head; (ver. 12,) those of an inferior condition, were sprinkled with ointment mixed with blood, &c. (Menochius)