וְהִלְבַּשְׁתָּ֙ אֶֽת־אַהֲרֹ֔ן אֵ֖ת בִּגְדֵ֣י הַקֹּ֑דֶשׁ וּמָשַׁחְתָּ֥ אֹת֛וֹ וְקִדַּשְׁתָּ֥ אֹת֖וֹ וְכִהֵ֥ן לִֽי׃
And thou shalt put upon Aaron the holy garments; and thou shalt anoint him, and sanctify him, that he may minister unto Me in the priest’s office.
Read kabbalistic (mystical) interpretation of Exodus 40:13: and classical mystical sources.