Ketubot 30A

חייבי עשה, מצרי ואדומי.

sex with women for which one is liable for violating a positive mitzva, e.g., an Egyptian convert and an Edomite convert (see Deuteronomy 23:8–9). If he raped a first- or second-generation Egyptian or Edomite convert, even R' Yeshevav agrees that the child is not a mamzer, as the betrothal takes effect. On the other hand, it is prohibited for him to sustain her as a wife.

הניחא לרבי ישבב, אי לאפוקי מטעמא דרבי סימאי קאתי ⁠— שפיר. אלא אי טעמא דנפשיה קאמר, כל שאין לו ביאה בישראל הולד ממזר ⁠— ואפילו חייבי עשה! מאי בינייהו?

The Talmud asks: This works out well according to R' Yeshevav if he is coming to reject the opinion of R' Simai. If R' Yeshevav merely takes issue with R' Simai, who said that all offspring of forbidden sex are mamzerim according to R' Akiva except for those resulting from sex between a widow and a High Priest, then it may well be explained that R' Yeshevav holds that R' Akiva rules that betrothal does not take effect and that there is mamzerut when one violates the prohibitions of the priesthood. However, if he is stating his own opinion, independent of R' Simai’s statement, his ruling is more comprehensive and leads to the conclusion that in the case of sex with anyone who does not have the possibility of permitted sex among the Jewish people, the child is a mamzer, and this is true even of women for sex with whom one is liable for violating positive mitzvot, e.g., Egyptian or Edomite converts. In that case, what is the difference between the opinions of Shimon HaTimni and R' Shimon ben Menasya?

איכא בינייהו בעולה לכהן גדול. ומאי שנא? דהוה ליה עשה שאינו שוה בכל.

The Talmud answers: There is a difference between them in the case of a non-virgin raped by a High Priest. And the Talmud asks: Here, too, she is a woman for sex with whom one is liable for violating a positive mitzva, as the High Priest fails to fulfill the mitzva “But a virgin of his own people should he take to wife” (Leviticus 21:14). If R' Akiva rules that betrothal does not take effect when a positive mitzva is violated, what is different about this case? The Talmud answers: It is different because it is a positive mitzva whose application is not equal for all. There are two lenient aspects to this mitzva: It is a positive mitzva and not a prohibition, and it applies only to the High Priest and not to all Jews. Even R' Yeshevav would agree that according to R' Akiva, a child born from sex between a High Priest and a non-virgin is not a mamzer. However, the High Priest may not sustain the woman as his wife. Therefore, this case is the practical difference between the statements of Shimon HaTimni and R' Shimon ben Menasya.