Talmud for Yevamot 15:4
הַכֹּל נֶאֱמָנִים לַהֲעִידָהּ, חוּץ מֵחֲמוֹתָהּ, וּבַת חֲמוֹתָהּ, וְצָרָתָהּ, וִיבִמְתָּהּ, וּבַת בַּעְלָהּ. מַה בֵּין גֵּט לְמִיתָה, שֶׁהַכְּתָב מוֹכִיחַ. עֵד אוֹמֵר מֵת, וְנִשֵּׂאת, וּבָא אַחֵר וְאָמַר לֹא מֵת, הֲרֵי זוֹ לֹא תֵצֵא. עֵד אוֹמֵר מֵת, וּשְׁנַיִם אוֹמְרִים לֹא מֵת, אַף עַל פִּי שֶׁנִּשֵּׂאת, תֵּצֵא. שְׁנַיִם אוֹמְרִים מֵת, וְעֵד אוֹמֵר לֹא מֵת, אַף עַל פִּי שֶׁלֹּא נִשֵּׂאת, תִּנָּשֵׂא:
All are trusted to testify (that her husband had died) except her mother-in-law, the daughter of her mother-in-law, her tzarah, her yevamah, and her husband's daughter. [The reason for all is that they hate her and desire her undoing. Her mother-in-law hates her, thinking: This one will "eat" all of my toil! The daughter of her mother-in-law hates her, thinking: This one will inherit all the toil of my father and mother! Her yevamah fears lest in the end she will be her tzarah. Her husband's daughter thinks: This one came in my mother's place and "ate" all of her toil!] What is the difference between get and death, [that we say that even those women who are not trusted to say that her husband has died are trusted to bring her get]? For the writing confirms it, [i.e., for we rely primarily upon the get (even though we also rely upon them, their being required to say: "Before me it was written, and before me it was signed.")] If one witness came and said: "He died, and she remarried," [not necessarily that she remarried, but that they permitted her to remarry], and another came and said that he did not die, she does not leave [her first sanction.] If one witness said that he died, and two said that he did not die, even if she had remarried, she is sent out. [This, in an instance where the two are unfit to testify. We are being apprised that since the Torah believed one witness (in this regard), the institution of witnesses does not (technically) obtain here, and that just as (the testimony of) one witness is entertained here, so (the testimony of) those unfit to testify is also entertained, and the majority deposition is followed, whether (the witnesses are) fit or unfit.] If two said he died, and one said that he did not die, even if she had not yet remarried, she may do so. [We are hereby apprised that the majority deposition is followed in an instance of unfit witnesses, whether for leniency or for stringency.]