Mishnayos Yevamos Perek 16 Mishnah 6

Witnesses may testify that an individual died even if they saw his corpse only by candlelight or by moonlight. And the court may allow a woman to marry based on the statement of a disembodied voice proclaiming that her husband died. There was an incident with regard to a certain individual who stood at the top of a mountain and said: So-and-so, son of so-and-so, from such and such a place died. They went and found no person there, but even so they relied upon the statement and allowed the wife of the individual declared dead to marry. And there was another incident in Tzalmon, a city in the Galilee, where a particular man said: I am so-and-so, son of so-and-so. A snake bit me and I am dying. And they went and found his corpse but could not recognize him, yet they went ahead and allowed his wife to marry based on what he said in his dying moments.

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: