2. Mose (Schemot) 40:15

וּמָשַׁחְתָּ֣ אֹתָ֗ם כַּאֲשֶׁ֤ר מָשַׁ֙חְתָּ֙ אֶת־אֲבִיהֶ֔ם וְכִהֲנ֖וּ לִ֑י וְ֠הָיְתָ֠ה לִהְיֹ֨ת לָהֶ֧ם מׇשְׁחָתָ֛ם לִכְהֻנַּ֥ת עוֹלָ֖ם לְדֹרֹתָֽם׃

and thou shalt anoint them, as thou didst anoint their father, that they may minister to me in the priest’s office: for their anointing shall be an everlasting priesthood throughout their generations.