Ketubot, Chapter Twelve, Mishnah Four
The last mishnah of this chapter deals with how long a widow has to collect her ketubah. As we shall see, this depends on whether she lives in her fathers house or remains in her husbands house.
1) As long as she lives in her fathers house she may collect her kethubah at any time.
a) As long as she lives in her husbands house she may recover her ketubah, only within twenty-five years, because in the course of twenty-five years she has sufficient opportunities to give favors equal [in value to the amount of] her ketubah, the words of Rabbi Meir who spoke in the name of Rabbi Shimon ben Gamaliel.
2) The Sages say: as long as she lives in her husbands house she may collect her ketubah at any time.
a) As long as she lives in her fathers house she may collect her ketubah only within twenty-five years.
3) If [the widow] died, her heirs must mention her ketubah within twenty-five years.
Section one: According to Rabbi Meir, if a widow returns to live in her fathers house she may collect her ketubah from her husbands inheritors even after 25 years. However, if she remains in her husbands home, if she doesnt collect the ketubah within twenty-five years, she forfeits it. The reason given is that in twenty-five years it can be assumed that she gave away to friends and neighbors property equal to the ketubah. Since this is technically not her money to give away, she loses her ketubah. In any case we should note that twenty-five years is quite a long time. Assumedly, a young widow who intended to remarry would have left her previous husbands home within the twenty-five years in any case. Furthermore, if she requests the ketubah in the twenty-fourth year, she receives the whole thing, even though she may have spent 24 years giving little things away to friends. In the end, this mishnah strikes me as quite generous to the widow.
Section two: The Sages posit an opposite system. According to them, the widow loses her ketubah after twenty-five years, not because we assume that she has given it away, but rather because after twenty-five years we can assume that she has forgiven the ketubah to her husbands inheritors. Therefore, if she remains at her husbands home she may always later decide to leave and collect her ketubah. The reason that she didnt ask for her ketubah earlier is that since she was living with the inheritors she may have been embarrassed to ask them. In contrast, if she lives at her fathers home, she has no excuse for not asking for it within twenty-five years, and hence after such a long time, the ketubah is considered to have been forgiven. Again, the important thing to realize is that which is unstated: a widow always has 25 years in which to collect her ketubah, no matter where she lives.
Section three: Although the widow herself sometimes has more than 25 years in which to collect the ketubah, should she die before she collects her ketubah, her inheritors must always stake a claim within this time. Some interpret this as 25 years within the death of the husband and some say it refers to 25 years from the death of the wife.