Throughout Massekhet Yevamot we have been learning the rules of the commandment of yibum – under what circumstances will a widow become a yevama who marries her late husband’s brother, when she is forbidden to him, etc.
What is the relationship between the yavam (the brother upon whom the commandment of yibum falls) and the yevama (the widow) prior to their fulfilling the commandment of yibum or, alternatively, their decision to perform halitza, which will effectively end their familial connection? Could the brother choose to marry one of the yevama’s immediate relatives (e.g. her mother or her sister), or would that be tantamount to marrying a forbidden woman to whom he is related through marriage?
To deal with this question, the Gemara introduces the concept of zika and teaches that there is an argument whether zika exists between the yavam and the yevama. Rav Huna quotes Rav as permitting the yavam to marry his yevama’s mother, indicating that he does not believe that zika exists between them. Rav Yehuda forbids such a marriage, which shows that, in his view, there is zika.
The word zika is a noun that expresses a theoretical relationship or connection, which – in its original meaning – indicates that one person is tied to another in some way (in modern Hebrew, for example, the word azikim means handcuffs or restraints). The Sages used the term less for its literal meaning and more to express a legal or emotional tie between people.
Our Gemara suggests that according to Rav Yehuda the zika is so strong – the bond is so substantial – that even if the woman dies, the potential yavam will not be allowed to marry her relatives, since we view it as though there was a relationship between them that was similar to marriage. The Talmud Yerushalmi, however, brings an opinion that even if you accept the concept of zika, in the event that the yevama dies, it becomes clear that the yibum relationship is never completed and the zika is retroactively annulled. Thus the surviving yavam would be permitted to marry the dead woman’s relative