Shemot 19:22

וגם הכהנים AND THE PRIESTS ALSO — the first born sons also, through whom the sacrificial service was carried out (Zevachim 115b), ‘הנגשים אל ה WHO MAY DRAW NIGH UNTO THE LORD to offer sacrifices — let them also not rely upon their rank and ascend the mountain, but יתקדשו LET THEM BE PREPARED to remain at their post, פן יפרץ LEST [THE LORD] BURST FORTH — The word פרץ is of the same root and meaning as פרצה “a breach”; the sense is: He may slay some of them and thus cause a breach in their ranks.

וְגַ֧ם הַכֹּהֲנִ֛ים הַנִּגָּשִׁ֥ים אֶל־יְהֹוָ֖ה יִתְקַדָּ֑שׁוּ פֶּן־יִפְרֹ֥ץ בָּהֶ֖ם יְהֹוָֽה׃

And let the priests also, who come near to the Lord, sanctify themselves, lest the Lord break forth upon them.