Q. After davening during Shabbat it is common in a shul to collect the sidurim or chumashim and placed them in order on the usual shelfs. Is there a problem of Borer (prohibited choosing act on Shabbat) especially at the night tefilah?

A. On question 2226 we wrote: Poskim rule that when sefarim are arranged in order on a shelf, one next to the other, since they are not piled or mixed, there is no borer involved and one may take the sefer he desires, even it is to be used later on. (Lehoros Nossan 3: 22, Meor Hashabbos 4, Maaseh Ish p. 109 quoting Chazon Ish and others).

However, some maintain that the above applies only when the name or the kind of a sefer can be easily recognized by its color or clear written title. Otherwise it may be considered as being in a mixed pile. (Shemiras Shabbos K’. 3: 220, quoting Horav S.Z. Auerbach zt’l),

When many sefarim are piled on a table, one on top of the other, it is prohibited in principle to pick them and organize them, if they are needed later on.
Poskim mention some exceptions. As when sidurim that are of one single nusach, but some are larger or newer and therefore in principle, could be readily be used by all. In that case, there may not be a issue of borer at all, since all sidurim are seen as only one single kind of items. (Piskei Teshuvos 319: n.191).

Others permit when one picks the different seforim one by one, and reads from each a bit, before he places it on their new selected location. (Oz Nidberu 8: 9, ibid: n. 192). Some maintain that just taking the very one on top of the pile each time, is not included in the borer prohibition (ibid. 193). There are opinions that are lenient, when the seforim find themselves in an exposed or dishonorable situation (Mishne Halochos 15: 114, Yabia Omer 5: 31, et al.).

Horav Shlomo Miller’s Shlit’a opinion is that one should be machmir and not reorder sidurim of a different nusach for later use., if they are not clearly and distinctly recognizable and well marked, However, one does not have to rebuke the one who is lenient and does so.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a