The Gemara in Masechet Yebamot cites and discusses a verse in which God says to Abraham that He will be "a God for you and for your offspring after you" (Bereshit 17:7). This verse indicates that the Almighty will be "God" only if one’s offspring is "after you," meaning, can be traced to the parents. The Gemara writes, "The Shechina resides only among the Meyuhasim of Israel." The term "Meyuhasim" refers to people who know with certainty who their parents are.

The practical application of this concept is a law enacted by the Sages forbidding a woman from remarrying after being widowed or divorced until ninety-two days have passed. If a woman marries within ninety-two days after a divorce or her husband’s death, and she becomes pregnant, we will be unable to definitively ascertain the identity of the child’s father. If she delivers the child seven months after her marriage to the second husband, the child could be either the son of the new husband – as it is possible to deliver a healthy baby after seven months of gestation – or the child conceived from the first husband nine months earlier, before the death or divorce. The Sages therefore required a woman to wait three months after a divorce or her husband’s death, as at this point it would be visible if she were pregnant. If she appears pregnant, then we can determine that the child was fathered by the first husband, and if she is not pregnant, then she may remarry and obviously any children she has will be identified as the children of the second husband. (We do not count the day of the death or divorce, or the day of her remarriage, as part of the required three-month period, and she must therefore wait ninety-two days, and not just ninety days.) This Halacha is codified in the Eben Ha’ezer section of the Shulhan Aruch (Siman 13).

It is customary to write in a Get (divorce contract) that the woman may not remarry for the next three months. In some places, the precise date when she becomes permissible to remarry is mentioned in the Get.

In the case of a divorcee, when precisely do we begin to count the ninety-two days?

Some authorities maintained that the counting begins from after the day the Get is written, regardless of when it is received by the woman, since the couple is forbidden to engage in relations already from that point. The Rosh (Rabbenu Asher Ben Yehiel, Germany-Spain, 1250-1327), however, held that the counting does not begin until the wife receives the Get, and this is the accepted opinion. (Nowadays, it is customary in any event to write the Get on the same day it is given.)

In light of this Halacha, it is critical for a Rabbi to conduct some research about the bride and groom before officiating at a wedding. When he is approached by a couple seeking to marry, he must inquire as to whether the bride had been previously married, and if she has, he must ascertain that ninety-two days have passed since the divorce or the death of the first husband.

It should be noted that ascertaining a child’s lineage is important also for another reason. If a child is assumed to be the son of a woman’s second husband, when in fact he the son of the first husband, he may unknowingly marry his paternal sister. Meaning, he may marry the daughter of the first husband from a different wife. As he assumes he was born from his mother’s second husband, he will not realize that he and this girl have the same father. For this reason, too, it is important for a woman to wait ninety-two days before remarrying, so we can definitively determine the father of her child.

Summary: After a woman is divorced or widowed, she may not remarry for ninety-two days, so that we can definitively determine the father of her child born after her remarriage.