Exodus 29:30

שבעת ימים SEVEN DAYS in succession, on such a High Priest’s installation, ילבשם הכהן THE PRIEST SHALL PUT THEM ON — i. e. he who, from among his sons, will rise up in his stead in the high-priesthood at the time when they will appoint him to be High Priest. אשר יבא אל אהל מועד WHO WILL COME INTO THE APPOINTED TENT — These words qualify the word הכהן so that it refers to that priest who is designated to enter into the innermost part (the words לפני ולפנים in the Rashi text correspond to בקדש in the Biblical text) of the Sanctuary on the Day of Atonement — and this must mean the High Priest, since the sacrificial service on the Day of Atonement was not valid unless performed by him (Yoma 73a). תחתיו מבניו IN HIS STEAD FROM AMONG HIS SONS — This informs us that if the High Priest has a son who can fill his place they shall appoint him High Priest in his stead (Sifra, Acharei Mot, Chapter 8 5; cf. Rashi on Yoma 72b). [הכהן תחתיו מבניו — From here (from this phraseology) we have a proof that the word הכהן is everywhere a participle — meaning “he who is actually acting as the officiant”; therefore the tonic accent תביר on the word הכהן connects it with the word following it.].

שִׁבְעַ֣ת יָמִ֗ים יִלְבָּשָׁ֧ם הַכֹּהֵ֛ן תַּחְתָּ֖יו מִבָּנָ֑יו אֲשֶׁ֥ר יָבֹ֛א אֶל־אֹ֥הֶל מוֹעֵ֖ד לְשָׁרֵ֥ת בַּקֹּֽדֶשׁ׃

And that son that is priest in his place shall put them on seven days, when he enters the Tent of Meeting to minister in the holy place.