Halakhah su Genesi 31:54

That a priest with a blemish not serve in the Temple: That a priest with a blemish not serve in the Temple service, as it is stated (Leviticus 21:17), "A man from your seed in their generations who has a blemish shall not approach to offer the bread of his God." [This is] meaning that he may not approach for the service, because all types of food are called bread in many places (see Rashi on Genesis 31:54). And this blemish [referred to in this context] is permanent. As so did they explain in Sifra, Emor, Section 3:5, "'Who has a blemish shall not approach' - I only have a permanent blemish. From where [do we know] a transient blemish? [Hence] we learn to say in the same section (Leviticus 21:18), 'any man who has a blemish shall not come close'" (meaning it is from another verse and not this one). And a permanent blemish is like a boil-scar or a protrusion, and that is a growth.