[If] a man fell into water, whether all its shores are in sight or not, his wife is prohibited. R' Meir said: There was [once] an incident where someone fell into a large well and surfaced after three days. R' Yose said: There was [once] an incident where a blind man descended into a cave to immerse himself, and was followed by his guide; they remained [undetected] long enough from them to have died, and [the Rabbis] permitted their wives to remarry. There was another incident at Asya, where someone was lowered into the sea and they recovered nothing but his leg. The Sages said: [If the leg was severed] above the knee, she may remarry; [if the leg was] below the knee, she may not remarry.

Even if he heard women saying, “So-and-so died,” it is sufficient. R' Yehudah says: Even if he heard children saying, “We are going to eulogize and bury so-and-so.” [His testimony is valid] whether he intends [to testify] or not. R' Yehudah ben Bava says: A Jew's [testimony is valid], even if he intended [to testify], but [if] a non-Jew intended [to testify], his testimony is not valid.