Talmud for Eduyot 3:6
הַשְּׁבוּיָה אוֹכֶלֶת בַּתְּרוּמָה, דִּבְרֵי רַבִּי דוֹסָא. וַחֲכָמִים אוֹמְרִים, יֵשׁ שְׁבוּיָה אוֹכֶלֶת וְיֵשׁ שְׁבוּיָה שֶׁאֵינָהּ אוֹכֶלֶת. כֵּיצַד. הָאִשָּׁה שֶׁאָמְרָה נִשְׁבֵּיתִי וּטְהוֹרָה אָנִי, אוֹכֶלֶת, שֶׁהַפֶּה שֶׁאָסַר הוּא הַפֶּה שֶׁהִתִּיר. וְאִם יֵשׁ עֵדִים שֶׁנִּשְׁבֵּית, וְהִיא אוֹמֶרֶת טְהוֹרָה אָנִי, אֵינָהּ אוֹכֶלֶת:
A captive woman [i.e., the wife of a Cohein, who had been taken captive,] eats terumah [and we do not fear that the gentile lived with her and rendered her a zonah, to whom terumah is forbidden.] These are the words of R. Dossa. And the sages say: There is a captive woman that eats, and a captive woman that does not eat. How so? A woman who says: "I was taken captive, but I am clean" eats. For "the tongue that forbids" [i.e., her saying "I was taken captive"] is the tongue that permits, [when she says "but I am clean." ] And if there were witnesses [that she was taken captive], and she says "I am clean," she does not eat.