It is permitted to place a Chumash on top of a sefer Tehillim, but one should not place a sefer Tehillim on top of a Chumash. The books of Nevi’im (Prophets) and Ketuvim (Writings) are equal in their sanctity; therefore one may place a Tehillim on top of books of Nevi’im and Ketuvim, and likewise one may place books of Nevi’im and Ketuvim on top of a Tehillim.
Sources and Explanations
The Shulchan Aruch (Yoreh De’ah 282:19) writes: “It is permitted to place a Sefer Torah on a Sefer Torah. One may place Chumashim on top of Nevi’im and Ketuvim, but one may not place Nevi’im and Ketuvim on top of Chumashim, nor Chumashim on top of a Sefer Torah.” The gloss (Hagah) adds: “But Ketuvim on top of Nevi’im, or the reverse, is permitted.”
The Magen Avraham (Orach Chaim 28:4) wrote that even though their sanctity is not equal, and one is slightly holier than the other, since the sanctity of one does not greatly exceed that of the other, one need not be particular about this; one must be particular only regarding something whose sanctity is far more severe, such as Torah compared to Nevi’im and Ketuvim.
From the sefer “Shaf Veyativ – Laws of Saying Tehillim” by Rabbi Shay Tahan, Chapter 8: The Sanctity of the Sefer Tehillim and Its Honor, Halacha 2 (p. 133 in the print edition). Translated from the Hebrew original.
