Yevamot 69A

מי שיש לו אלמנות וגירושין בה, יצאו גוי ועבד שאין לו אלמנות וגירושין.

This verse is referring to a man who has potential widowhood and divorce with her, excluding a non-Jew and a slave, who do not have widowhood and divorce with her, as they cannot marry Jews at all. Therefore, they disqualify a woman from marrying into the priesthood through sex, even if she does not have a child with them.

אשכחן כהנת ⁠— לויה וישראלית מנא לן? כדאמר רבי אבא אמר רב: ״בת״ ״ובת״, הכא נמי ״בת״ ״ובת״.

The Talmud asks: We have found a source for the halakha that a non-Jew and a slave disqualify a priestess. From where do we derive this with regard to a Levite and an Israelite woman? The Talmud answers: It is as R' Abba said that Rav said: The verse “But if a priest’s daughter be a widow, or divorced” (Leviticus 22:13) could have begun with the words: If a priest’s daughter. The word “but,” the prefix vav, expands the prohibition to include additional women. Here too, it may be derived from the distinction between the phrase: If a priest’s daughter, and the phrase as it actually appears in the verse: “But if a priest’s daughter,” that Levite and Israelite women are subject to the prohibition as well.

כמאן ⁠— כרבי עקיבא דדריש ווי? אפילו תימא רבנן ⁠— כולה ״ובת״ קרא יתירא הוא.

The Talmud asks: In accordance with whose opinion is this exposition possible? It is in accordance only with the opinion of R' Akiva, as he derives halakhot from the prefix vav. The Talmud responds: Even if you say it is accordance with the Rabbis, the entire phrase: “But if a priest’s daughter,” is superfluous in the verse, as the previous verses had already mentioned the priest’s daughter. Therefore, the inclusion of Levite and Israelite women in the prohibition may be derived from the entire expression.