קְדֹשִׁ֤ים יִהְיוּ֙ לֵאלֹ֣הֵיהֶ֔ם וְלֹ֣א יְחַלְּל֔וּ שֵׁ֖ם אֱלֹהֵיהֶ֑ם כִּי֩ אֶת־אִשֵּׁ֨י יְהוָ֜ה לֶ֧חֶם אֱלֹהֵיהֶ֛ם הֵ֥ם מַקְרִיבִ֖ם וְהָ֥יוּ קֹֽדֶשׁ׃
They shall be holy unto their God, and not profane the name of their God; for the offerings of the LORD made by fire, the bread of their God, they do offer; therefore they shall be holy.
Sifra
6) (Vayikra 21:6) "Holy shall they be to their G d": perforce (i.e., even if they are willing to be unclean) "and they shall not profane the name of their G d; for the fire-offering of the L–rd, the bread of their G d, they offer up — and they shall be holy": This is the cause (i.e., by divesting themselves of the mitzvah of the priesthood, they divest themselves of their holiness.) "they offer up": and not the Levites. "and they shall be holy": to include those with blemishes.