Kiddushin, Daf Samekh Heh, Part 2
Introduction
The Talmud begins to explain the mishnah.
גמ׳ האומר לאשה קדשתיך וכו’
וצריכא דאי אשמעינן גביה דידיה משום דגברא לא איכפת ליה ומיקרי אמר אבל איהי אימא אי לאו דקים לה בדיבורה לא הות אמרה וליתסר איהו בקרובותיה קמ"ל
GEMARA. If he says to a woman, I have betrothed you etc. [Both clauses] are necessary. For if it taught us this about him, [that is] because a man does not care [about making such a statement], and so it happens that he might say this. But as for her, I might have said, were she not certain of her statement, she would not have said it, and so her relations are forbidden to him.
Hence it teaches us [that this is not so].
Why did the mishnah need to teach the same rule with regard to him and with regard to her?
The answer is that if the mishnah had taught it only with regard to the man, we might have thought that the man does not care about happening to say that he is betrothed to a woman when he is not. He can always betroth another one. So we would not believe him and therefore she is permitted to marry his relatives. But the consequences for a woman to say I was betrothed to a certain man are greater, for now she cannot marry anyone. Therefore, we might have believed her and said that he is prohibited to her relatives. We would assume based on her word that they indeed are betrothed. Therefore, we need to say that she too is not believed vis a vis other people.
קידשתיך והיא אומרת וכו’ הא תו למה לי איצטריך ס"ד אמינא מדאורייתא הימניה רחמנא לאב מדרבנן הימנוה לדידה ותיתסר ברתה בדיבורה קא משמע לן
I have betrothed you, and she replies etc.
Why do I need this too?
It is necessary. Lest I would have said law the Torah believed the father and the rabbis believed her [the mother], and so her daughter is prohibited on her statement.
Hence it teaches us [otherwise].
Why does the mishnah need another example of the same principle? Why does it need to teach us that if the mother says the daughter was betrothed to this man, the mother is not believed vis a vis the daughter?
The answer is that the rabbis did give the mother the power to betroth the daughter when the father is no longer alive. So we might have thought that the mother is believed and creates a prohibition for her daughter. Therefore, the mishnah teaches that she is not.
קידשתי את בתך וכו’ הא תו למה לי איידי דתנא הא תנא נמי הא
I have betrothed your daughter etc. Why do I need another example? Since the one is taught, the other is taught too.
This section of the mishnah is indeed repetitive we did not need another example. But it is taught anyways, just for a sense of completion.