Exodus 29:29

לבניו אחריו [SHALL BE] FOR HIS SONS AFTER HIM — for him who comes after him in this high office. למשחה means to be raised to dignity by means of them. For sometimes the word משח is used in the sense of “dignity”, as in (Numbers 18:8), “to thee I have given them as a dignity (למשחה)”, and (I Chronicles 16:22) “Touch ye not my nobles (משיחי)” (cf. Rashi on Exodus 30:29). ולמלא בם את ידם AND TO BE CONSECRATED BY THEM — through these garments he is to be invested with the high-priesthood (cf. Rashi on Yoma 73a).

וּבִגְדֵ֤י הַקֹּ֙דֶשׁ֙ אֲשֶׁ֣ר לְאַהֲרֹ֔ן יִהְי֥וּ לְבָנָ֖יו אַחֲרָ֑יו לְמׇשְׁחָ֣ה בָהֶ֔ם וּלְמַלֵּא־בָ֖ם אֶת־יָדָֽם׃

And the holy garments of Aharon shall be his sons’ after him, to be anointed in them, and to be consecrated in them.