How did Martin Buber differ from Franz Rosenzweig in practicing Judaism?

The primary difference between Martin Buber and Franz Rosenzweig regarding the practice of Judaism lay in their approach to religious law and tradition.

While both were influential thinkers and collaborators on a German translation of the Hebrew Bible, their personal commitments to Jewish observance diverged significantly:

• Martin Buber: He maintained a stance of "religious anarchism," rejecting fixed rules of behavior or dogmatic prescriptions in the relationship between humanity and God. He embodied his Judaism without adhering to a prescribed, special manner of observance, often criticizing traditional legalistic interpretations as being removed from a true "I–Thou" encounter with the divine.1
• Franz Rosenzweig: In contrast, Rosenzweig increasingly embraced the practice of Judaism throughout his life. He sought to live out the tradition as much as possible, becoming a deeply practicing Jew who found meaning in the rhythm of the Jewish liturgical year and the vitality of classical Hebrew sources.123

This fundamental disagreement led to a famous exchange where Rosenzweig argued that Buber, while elevating the "Thou," unfairly neglected the importance of the "It"—the concrete, normative aspects of religious life.1