Sefer HaChinuch ספר החינוך

That a priest with a transient blemish not serve: That a priest with a transient blemish not serve, as it is stated (Leviticus 21:21), “Any man that has a blemish from the seed of Aharon the priest shall not come forth” — [the] word, “any,” is an inclusion; and it includes a transient blemish. As at the beginning, it warns about a permanent blemish, such that I would reason that it is permitted to serve with a transient blemish which is less weighty than it. Therefore it warned about the transient, and that is the garav and the yalefet.

Similar to what we wrote about the commandment previous to it is from the roots of the commandment.

From the laws of the commandment is that which they, may their memory be blessed, said (Kiddushin 66b) that both one with a permanent blemish or [one with] a transient blemish disqualifies the service and is lashed — if he served (transgressed) volitionally. And that which they, may their memory be blessed, said (Mishnah Middot 5:4) that the Great Court would sit in the chamber of hewn stone and their main constant activity was to check the priests in their pedigree and their blemishes. And any priest that was found to be disqualified in his pedigree wears black, wraps himself in black and goes out of the [Temple] yard. But one found complete and fit wears white, enters and serves with his brother priests. And one who was found fit in his pedigree but a blemish was found on him sits in the chamber of wood and removes the wormy wood for the arrangement [of wood]. And he divides the holy foods with his clan and eats, as it is stated (Leviticus 21:22), “The bread of His God from the holy of the holies and from the holy he may eat.” And the rest of the laws of all of the blemishes are in Bekhorot, the seventh chapter.

And [it] is practiced at the time of the [Temple] by the priests. If he transgressed and served with a transient blemish volitionally, he is lashed. And Ramban, may his memory be blessed, (on Sefer HaMitzvot, Negative Commandments 71) does not count the negative commandment of a transient blemish as a negative commandment on its own. And he wrote that it is included in the negative commandment of a permanent blemish, and that it is like a section of the [various] sections of the commandment. And he and Rambam, may his memory be blessed, (Sefer HaMitzvot, Shorashim 11), have already agreed — and it is a clear thing - that we should not consider a section of a commandment, a commandment on its own.