Midrash su Levitico 21:7

4) "a zonah": Why is this written? (i.e., I can derive it a fortiori from her being forbidden to an ordinary Cohein.) For I might think that only the seed of a high-priest by those unfit for him become challalim. Whence do I derive the same for the seed of an ordinary Cohein? It is, therefore, written "zonah" (here) and "zonah" (Vayikra 21:7, in respect to an ordinary Cohein), for a gezeirah shavah (identity). Just as the seed of a high-priest by those unfit for him are challalim, so, the seed of an ordinary Cohein.

7) (Vayikra 21:7) ("A woman who is a zonah and a challalah they shall not take, and a woman divorced from her husband they shall not take; for he is holy to his G d.") "a woman who is a zonah": R. Yehudah says: This is an aylonith (a barren woman [i.e., the term "zonah" also includes an aylonith]). And the sages say: This is a proselytess or a freed maidservant or one whose cohabitation was one of znuth (i.e., illicit). R. Eliezer says: Also (included) is cohabitation of a single man with a single woman not for the sake of marriage.

Wilt Thou, indeed, sweep away the righteous with the wicked? What is implied by this verse? That he spoke harshly to Him and said: Anger consumes a human being, but is it possible that you are so angry that you would sweep away the righteous with the wicked? Would You judge the innocent as You judge the wicked? Would You destroy the innocent and the evil together? It is far from Thee to do after this manner (Gen. 18:25). Since the Hebrew word hallilah (“it is far from thee”) contains the letters of the word hallalah (“profaned”), as in the verse A woman that is a harlot, or profaned (Lev. 21:7), this verse implies that he was suggesting, “Would it not be a profanation of Your name if You were to act in this manner? Did You do that with the generation of the flood, or the generation of the separation? Surely, that is not Thy way.”