No descendant of Aaron the priest who has a defect shall approach to present the food offerings to the LORD. Since he has a defect, he is not to come near to offer the food of his God.
The priesthood being confined to one particular family, and entailed upon all the male issue of that family throughout their generations, it was very likely that some or other in after-ages that were born to the priesthood would have natural blemishes and deformities: the honour of the priesthood would not secure them from any of those calamities which are common to men.
Commenting on Leviticus 21:16-24
He shall eat the bread of his God,.... That part of the sacrifices which was appropriated by the Lord to the priests, for the maintenance of them and their families; for though their natural infirmities disqualified them for service, yet they did not become hereby impure, either in a moral nor ceremonial sense, and might eat of the sacrifices, which impure persons might not; and...
No man that hath a blemish of the seed of Aaron the priest shall come nigh to offer the offerings of the LORD made by fire: he hath a blemish; he shall not come nigh to offer the bread of his God. (p) As the show bread, and meat offerings.