179 Yevamot 16/6

(ו) מְעִידִין לְאוֹר הַנֵּר וּלְאוֹר הַלְּבָנָה, וּמַשִּׂיאִין עַל פִּי בַת קוֹל. מַעֲשֶׂה בְאֶחָד שֶׁעָמַד עַל רֹאשׁ הָהָר וְאָמַר, אִישׁ פְּלוֹנִי בֶן פְּלוֹנִי מִמָּקוֹם פְּלוֹנִי מֵת, הָלְכוּ וְלֹא מָצְאוּ שָׁם אָדָם, וְהִשִּׂיאוּ אֶת אִשְׁתּוֹ. וְשׁוּב מַעֲשֶׂה בְצַלְמוֹן בְּאֶחָד שֶׁאָמַר, אֲנִי אִישׁ פְּלוֹנִי בֶּן אִישׁ פְּלוֹנִי, נְשָׁכַנִי נָחָשׁ, וַהֲרֵי אֲנִי מֵת, וְהָלְכוּ וְלֹא הִכִּירוּהוּ, וְהִשִּׂיאוּ אֶת אִשְׁתּוֹ:

(6) One may testify [even if he only saw the corpse] by the light of a candle or by the light of the moon. And we permit a woman to marry [even if the report of her husband's death] is based on a heavenly voice. It once happened that an individual stood on a mountain peak and said, "So-and-so the son of so-and-so from such-and-such a place died". They went but could find nobody there and they allowed his wife to marry. And another incident happened in Tzalmon with an individual who said, "I, So-and-so the son of so-and-so was bitten by a snake and I am dying". And they went [and found him] but they could not recognize him, and they allowed his wife to marry.