The practice of reciting Tehillim (Psalms) for the sick is not originally Jewish—it actually began in Christian liturgy. Early Christians would recite Psalms on behalf of the ill, and eventually replaced them with repeated “Hail Marys,” leaving the Psalms behind.
In Judaism, the Talmud explicitly prohibits using verses of Tanach as a cure. The Rambam (Hilchot Avodah Zarah 11:12) rules:
“One who whispers over a wound and recites a verse from the Torah, or reads a verse over a child so that he will not be afraid, or places a Torah scroll or tefillin over a child so that he will sleep, is not only among those who practice sorcery but also among those who deny the Torah, for they make the words of Torah into a bodily remedy, when they are only remedies for the soul.”
And the Shulchan Aruch (Yoreh De’ah 179:8) codifies:
“It is forbidden to recite verses from the Torah as a cure, or to place a Torah scroll or tefillin upon a child so that he may sleep.”
Yet the Rambam continues there:
“But a healthy person who reads verses of the Torah or recites Psalms so that the merit of reading them should protect him and save him from difficulties and injury, this is permitted.”
This distinction is crucial. Saying Tehillim for the healthy is legitimate, but saying Tehillim for the sick is explicitly forbidden. That shows beyond doubt that the Rambam is talking about Psalms themselves—not some other verses—and that the prohibition is not against “prayer” in general, but against turning Tehillim into a healing incantation.
Despite this, in later generations it became customary in Jewish communities to say Tehillim for the sick. This is one of those places where what is presented as “Judaism” is not the reality of Torah law. Much confusion has crept in, and people do things the Torah says are prohibited—yet nobody objects.
My father, Rabbi Yitzhak Abadi, was strongly opposed to this practice, as was Rav Shlomo Zalman Auerbach. Both were attacked for taking this stand—especially my father—because people have come to believe that customs override halachah. But that reasoning is absurd. If custom overrides halachah, then the generations of idol worship in Tanach should also be legitimate, since idolatry was the “custom” of the time. Clearly, Torah law—not popular custom—defines authentic Judaism.