Yevamot, Chapter Fifteen, Mishnah Three
In the previous mishnah Bet Hillel agreed with Bet Shammai that a woman who states that her husband died is to be believed, at least in most cases. In our mishnah, Bet Hillel states that her testimony allows her to remarry but not to receive her ketubah payment, the amount that a man owes a woman upon death or divorce. Bet Shammai holds that she also receives her ketubah payment. As in the previous mishnah, in the end Bet Hillel changes their opinion and agrees with Bet Hillel.
1) Bet Shammai says: she may marry and she receives her ketubah.
a) Bet Hillel says: she may marry but she does not receive her ketubah.
2) Bet Shammai said to them: you have permitted [what might be] the serious consequence of illicit intercourse, why should you not permit [the taking of her husbands] money which is of less consequence!
a) Bet Hillel said to them: we find that based on her testimony, the brothers may not receive their inheritance.
b) Bet Shammai said to them: do we not learn this from her ketubah scroll wherein [her husband] writes to her if you are married to another man, you will receive what is prescribed for you!
3) Bet Hillel changed their view to rule in accordance with Bet Shammai.
Section one: This section delineates the dispute between the two houses, as explained in the introduction above.
Section two: Bet Shammai reasons that if she was not telling the truth about her husband dying (either by intentionally lying or by having made a mistake) the consequences of her remarrying are graver than the consequences of her illegitimately taking money from her husband. Remarrying while still married is adultery, and if done with intention can be a capital offense. The monetary crime of taking her ketubah while her husband is still alive is at worst fraud, and the money can always be rightfully restored. Since the Sages allow her to remarry, despite the potential severity of the crime, they must allow her to recover her ketubah payment.
Bet Hillel responds by citing a precedent. According to the accepted halakhah, a halakhah to which Bet Shammai agrees, when a woman testifies that her husband has died, his brothers do not inherit his money. This is because in monetary cases two witnesses are required. [Note: a mans brothers inherit him if he did not have children.] Therefore, just as the brothers do not collect their inheritance, so too the woman does not collect her ketubah.
Bet Shammai responds by citing the actual ketubah wording which states that if she marries another man she may collect the payment. Therefore, according to Bet Shammai, as soon as she is permitted to marry someone else, she may collect her ketubah. We should note that this is an interesting source of halakhah: the wording of the ketubah. Generally we would think that the halakhah would dictate the wording of the ketubah, but here we find the opposite. The ketubah, a secular document, becomes the source of Jewish law. This is not a common phenomenon in rabbinic literature but is found in several other places.
Section three: Bet Hillel again changed their minds and ruled as did Bet Shammai. Therefore, even though the brothers do not receive their inheritance, the wife may collect her ketubah.