Kiddushin 67B

״כל מקום״ דסיפא ⁠– לאתויי גר שנשא ממזרת. אלא אי אמרת רבי יוסי היא, ״כל מקום״ דרישא ⁠– כדאמרן, ״איזו זו״⁠ – כדאמרן, אלא ״כל מקום״ דסיפא לאתויי מאי?

And the phrase: Any case, of the latter clause, which is referring to betrothal with a transgression, serves to include a convert who married a mamzeret. But if you say that the Mishnah is in accordance with the opinion of R' Yosei, then granted the phrase: Any case where there is betrothal and no transgression, of the first clause, is as we said, i.e., it includes an Israelite who married a ḥalala; and the phrase: In which case is this applicable, is as we said, i.e., to the exclusion of Ravin or Rav Dimi, and the case of a convert who married a mamzeret. But what does the phrase: Any case, of the latter clause, serve to add?

ולטעמיך, לרבי יהודה ״איזו זו״ דסיפא למה לי? אלא: איידי דתנא רישא ״איזו זו״, תנא סיפא ״איזו זו״. הכי נמי איידי דתנא רישא ״כל מקום״, תנא נמי סיפא ״כל מקום״.

The Talmud responds: And according to your reasoning, the same question applies to R' Yehuda as well: Why do I need the phrase: In which case is this applicable, of the latter clause? Rather, you must say: Since the Mishnah taught its first clause using the phrase: In which case is this applicable, it also taught its latter clause using the phrase: In which case is this applicable, merely for the sake of stylistic consistency. So too here, with regard to R' Yosei’s opinion, one can say: Since the Mishnah taught the first clause with the expression: Any case, it also taught its latter clause with: Any case.

גופא: כי אתא רבין, אמר רבי יוחנן: באומות ⁠– הלך אחר הזכר. נתגיירו ⁠– הלך אחר הפגום שבשניהם.

§ The Talmud discusses the aforementioned matter itself: When Ravin came from Eretz Yisrael, he said that R' Yoḥanan says: With regard to the nations, if members of two different nations married when they were non-Jews, follow the male to determine the status of their child. If they converted before marriage, follow the flawed lineage of the two.