Charles Ellicott Commentary Numbers 20:26

"and strip Aaron of his garments, and put them upon Eleazar his son: and Aaron shall be gathered [unto his people], and shall die there." — Numbers 20:26 (ASV)

And strip Aaron of his garments.— Thus the same hands that had invested Aaron with the sacred garments were employed in divesting him of them, and, in both cases, in obedience to the express command of God. The removal of the priestly robes from Aaron may be regarded as typical of the future disannulling of his priesthood when a priest after the order of Melchizedek should arise. “The succession of the priesthood,” says Dean Stanley (who refers to Ewald’s Geschichte, 5:13), “was made through that singular usage, preserved even to the latest days of the Jewish hierarchy, by the transference of the vestments and drapery of the dead High Priest to the living successor.” (Lectures on Jewish History, 1:182.)