Responsum: On the Status of a Talmud Codex
Question: You asked about the statement of the sages:
One may place a Torah scroll upon a scroll of the Prophets. [b. Megillah 27a]
Is the status of volumes of the Talmud like that of Torah scrolls with regard to this law?
Answer: When the sages said that one may place a Torah scroll upon the Prophets, they were referring only to the Torah itself. The Talmud, however, is the clarification and interpretation of the Torah, not the actual Torah. Thus, for example, it does not render the hands ritually impure and does not require writing on ruled lines like the actual Torah. You can infer from these laws that its holiness is less than that of the Torah itself, and indeed, it is not as sacred as the other books of the holy scriptures. In light of the fact that it does not render the hands ritually impure, and also that it does not require ruled lines, it can be concluded that one may not place the Talmud even upon the Writings, and all the more so upon the Prophets, and certainly not upon the Torah.
Published in: The Posen Library of Jewish Culture and Civilization, vol. 3: Encountering Christianity and Islam.