Talmud for Ketubot 12:4
כָּל זְמַן שֶׁהִיא בְבֵית אָבִיהָ, גּוֹבָה כְתֻבָּתָהּ לְעוֹלָם. כָּל זְמַן שֶׁהִיא בְּבֵית בַּעְלָהּ, גּוֹבָה כְתֻבָּתָהּ עַד עֶשְׂרִים וְחָמֵשׁ שָׁנִים, שֶׁיֵּשׁ בְּעֶשְׂרִים וְחָמֵשׁ שָׁנִים שֶׁתַּעֲשֶׂה טוֹבָה כְנֶגֶד כְּתֻבָּתָהּ, דִּבְרֵי רַבִּי מֵאִיר שֶׁאָמַר מִשּׁוּם רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל. וַחֲכָמִים אוֹמְרִים, כָּל זְמַן שֶׁהִיא בְּבֵית בַּעְלָהּ, גּוֹבָה כְתֻבָּתָהּ לְעוֹלָם. כָּל זְמַן שֶׁהִיא בְּבֵית אָבִיהָ, גּוֹבָה כְתֻבָּתָהּ עַד עֶשְׂרִים וְחָמֵשׁ שָׁנִים. מֵתָה, יוֹרְשֶׁיהָ מַזְכִּירִין כְּתֻבָּתָהּ עַד עֶשְׂרִים וְחָמֵשׁ שָׁנִים:
So long as she is in her father's house [and the heirs feed her there], she can always [i.e., whenever she wishes] claim her kethubah. So long as she is in her husband's house, she can claim her kethubah for twenty-five years; for there is in the twenty-five years (enough time) for her to do good against (the amount of) her kethubah. These are the words of R. Meir in the name of R. Shimon b. Gamliel. And the sages say: So long as she is in her husband's house, she can always claim her kethubah. So long as she is in her father's house, she can claim her kethubah for twenty-five years. [The twenty-five years were not mentioned to cause her to lose her kethubah because of the good she does from the property of the orphans, but (they were mentioned) in respect to "waiving" (the kethubah), i.e., since she remained silent and did not claim it all of these years, she has waived it. Therefore, so long as she is in her husband's house, her silence does not constitute "waiving," for since they honor her, she is ashamed to claim her kethubah. But in her father's house, if she remained silent for twenty-five years, this constitutes "waiving."] If she died, her heirs "mention" her kethubah for twenty-five years. [That is, they must claim her kethubah within twenty-five years. And this is only when she swore to (not having collected) her kethubah before she died. But if she had not sworn to her kethubah, her heirs collect nothing of it, for "a man does not bequeath an oath to his sons."]