Leviticus 21:6

They shall be holy unto their God
Sacred to his service, and wholly given up to it, and not interest themselves in things which hindered from it, or made them unfit for it; and such care becomes the ministers of the word, who should give up themselves to it, and not entangle themselves with other affairs; they should be clean, pure, and holy, that bear the vessels of the Lord, and minister in holy things, and should set an example of purity and holiness to others: and not profane the name of their God;
or cause it to be profaned and evil spoken of on their account, or his service to be interrupted, and they who bore his name put upon a level with common persons through their pollutions: for the offerings of the Lord made by fire;
the burnt offerings, which were offered up to the Lord on the altar of burnt offering every day, besides others on divers occasions: [and] the bread of their God do they offer;
the shewbread, which they set every week before the Lord on the shewbread table, and the meat or bread offering, the "minchah", which they continually offered along with the sacrifices: or the word "and", being a supplement, may be left out; and so this clause is put by way of apposition, and as interpreting the fire offering to be the bread of their God, which being wholly burnt on the altar, and devoted to God, was his meat and food, and accepted by him, see ( Leviticus 3:11 ) ; therefore they shall be holy;
separate from all others, and abstain from all impurity both of flesh and spirit, from all uncleanness, moral and ceremonial; it being highly fit and proper that the bread of God should be offered by holy persons.