출애굽기 19:22의 주석

וגם הכהנים AND THE PRIESTS ALSO — the first born sons also, through whom the sacrificial service was carried out (Zevachim 115b),

AND THE PRIESTS ALSO, THAT COME NEAR TO THE ETERNAL. I.e., who offer the sacrifices to the Glorious Name²⁵⁹Deuteronomy 28:58. and who come near to Him with them. [They also must sanctify themselves and not go outside of their designated place.]

וגם הכהנים הנגשים אל ה׳ יתקדשו, "And also the priests who approach G'd have to sanctify themselves, etc." Although the priests (the firstborn in the main) are closer to G'd than the people at large, being allowed to perform sacrificial service in sacred locations, they too have to undergo a special sanctification process prior to the revelation. The fact that they normally adhered to strict standards of purity was not enough in this instance. They had to consider themselves as no better than the people at large. The meaning of the word יתקדשו is similar to the meaning of the word ודשנו in Numbers 4,13 where the priests are described as removing the ashes from the altar. The priests too had to remove themselves from the Mountain.