Reference for Ketubot 9:8
הַפּוֹגֶמֶת כְּתֻבָּתָהּ כֵּיצַד, הָיְתָה כְתֻבָּתָהּ אֶלֶף זוּז, וְאָמַר לָהּ הִתְקַבַּלְתְּ כְּתֻבָּתֵךְ, וְהִיא אוֹמֶרֶת לֹא הִתְקַבַּלְתִּי אֶלָּא מָנֶה, לֹא תִפָּרַע אֶלָּא בִשְׁבוּעָה. עֵד אֶחָד מְעִידָהּ שֶׁהִיא פְרוּעָה כֵּיצַד, הָיְתָה כְתֻבָּתָהּ אֶלֶף זוּז, וְאָמַר לָהּ הִתְקַבַּלְתְּ כְּתֻבָּתֵךְ, וְהִיא אוֹמֶרֶת לֹא הִתְקַבָּלְתִּי, וְעֵד אֶחָד מְעִידָהּ שֶׁהִיא פְרוּעָה, לֹא תִפָּרַע אֶלָּא בִשְׁבוּעָה. מִנְּכָסִים מְשֻׁעְבָּדִים כֵּיצַד, מָכַר נְכָסָיו לַאֲחֵרִים, וְהִיא נִפְרַעַת מִן הַלָּקוֹחוֹת, לֹא תִפָּרַע אֶלָּא בִשְׁבוּעָה. מִנִּכְסֵי יְתוֹמִים כֵּיצַד, מֵת וְהִנִּיחַ נְכָסָיו לַיְתוֹמִים, וְהִיא נִפְרַעַת מִן הַיְתוֹמִים, לֹא תִפָּרַע אֶלָּא בִשְׁבוּעָה. וְשֶׁלֹּא בְּפָנָיו כֵּיצַד, הָלַךְ לוֹ לִמְדִינַת הַיָּם, וְהִיא נִפְרַעַת שֶׁלֹּא בְפָנָיו, אֵינָהּ נִפְרַעַת אֶלָּא בִשְׁבוּעָה. רַבִּי שִׁמְעוֹן אוֹמֵר, כָּל זְמַן שֶׁהִיא תוֹבַעַת כְּתֻבָּתָהּ, הַיּוֹרְשִׁין מַשְׁבִּיעִין אוֹתָהּ. וְאִם אֵינָהּ תּוֹבַעַת כְּתֻבָּתָהּ, אֵין הַיּוֹרְשִׁין מַשְׁבִּיעִין אוֹתָהּ:
"If a woman impairs her kethubah": How so? If her kethubah were a thousand zuz, and she said: I received only one hundred, she exacts payment only with an oath. "If one witness testifies that it has been paid": How so? If her kethubah were a thousand zuz, and he said to her: You have received your kethubah, and she said: I did not receive it, and one witness testifies that it was paid, she exacts payment only with an oath. "from bound property": How so? If he sold his property to others, and she claims payment from the receivers, she can exact payment only with an oath. "from the property of the orphans": How so? If he died and left his property to the orphans, and she claims payment from the orphans, she can exact payment only with an oath. "not in his presence": How so? If he went abroad, and she claims, not in his presence, she can exact payment only with an oath. R. Shimon says: Whenever she claims her kethubah, the heirs can make her swear; and if she does not claim her kethubah, the heirs cannot make her swear. [This refers to the ruling of the rabbis (9:4): "If one sets up his wife as a shopkeeper or as a caretaker, he can administer an oath to her whenever he wishes," and (9:5): "If he wrote: 'Neither I nor my heirs will impose either vow or oath upon you,' the heirs cannot make her swear." He (R. Shimon) comes to differ and to say that whenever she claims her kethubah, the heirs can make her swear, even if he wrote: "Neither I nor my heirs will impose vow nor oath upon you." And if she does not claim her kethubah, the heirs cannot make her swear as to her caretakership in her husband's lifetime, even if he (himself) did not exempt her from an oath, R. Shimon differing from R. Eliezer and those of his opinion who say (9:4): "He can administer an oath to her whenever he wishes." The halachah is not in accordance with R. Shimon.]