Ketubot, Chapter Two, Mishnah Five
This mishnah continues to discuss cases that illustrate the principle the mouth that forbade was the mouth that permitted.
1) If a woman says, I was married and I am divorced, she is believed, for the mouth that forbade is the mouth that permitted.
a) But if there are witnesses that she was married, and she says, I am divorced, she is not believed.
2) If she says, I was taken captive but I have remained clean, she is believed, for the mouth that forbade is the mouth that permitted.
a) But if there are witnesses that she was taken captive and she says, I have remained clean she is not believed.
b) But if the witnesses came after she had married, she shall not go out.
Section one: If the woman herself provides the information that she was married, but then says she is now single because she was divorced, she is believed, because the same mouth that permitted, forbade. However, if other witnesses testify that she was married, she is not believed when she says she is divorced. In order to remarry, she will need to bring proof, either with a document or witnesses.
Section two: If a woman is taken captive by a non-Jew, she is assumed to have been raped and is subsequently forbidden to marry a priest. This is because she has had forbidden sexual relations, and priests cannot marry anyone who has had relations with some forbidden to them, even if the relations were against her will. If the woman says that she was taken captive, and that information is not otherwise known, she is now the mouth that forbade. Hence, when she says that she remained clean, i.e. she was not raped, she is believed and she can marry a priest. However, if other witnesses testify that she was taken captive, she is no longer the mouth that forbade. Therefore, she is not believed to permit herself to a priest.
If before the witnesses come and state that she was taken captive, she marries a priest, he is not obligated to divorce her. This is because it is not certain that she was raped. The Talmud says that even if she received permission to remarry before the witnesses came, she may marry a priest. According to the Talmud, what is essential is that at the point when she was the mouth that permitted there was not an earlier mouth that forbade. Therefore, as long as she makes her statement before the witnesses come, she will be allowed to marry a priest.