The main reason for mentioning the mother and not the father of the ill person is the verse, "bring salvation to the son of Your maidservant,"¹ which specifies the mother.

Another reason for specifying the mother is because we can be sure who the person’s mother is, whereas the father’s identity is never unquestionable. Obviously when praying for someone’s life, we do not want to confuse his/her identity through using mistaken lineage. Another related reason is that a Jew’s spiritual essence is inherited via his or her mother (whereas the father determines tribal association). When we pray for someone’s life, we want to emphasize their essential and eternal link to G-d, as derived from their mother’s side.

A Jew’s spiritual essence is inherited via his or her mother. When we pray for someone’s life, we want to emphasize their essential and eternal link to G-d, as derived from their mother’s side

Another reason: Since we are beseeching Heaven for mercy, we want to bring as little critical attention to the sick person as possible. Since women have less Mitzvah obligations, thus lowering their likelihood to sin, it is usually less spiritually incriminating to mention a person’s mother.

In a case when the person’s mother’s name is entirely unknown, the ill person’s name should be appended with “…ben (or bat) Sarah,” referring to the matriarch Sarah, who is the mother of all Jewish people. If the mother’s non-Jewish name is known, however, it should be mentioned, as in “…ben (or bat) Elizabeth.”

May we only need pray for continued good health for us all!