[The Laws Regarding] That One Should Not Interrupt With Piyyutim. Containing 1 Se'if
There are places where they interrupt the blessings of the Shema in order to say piyyutim (liturgical poems), but it is proper to refrain from saying them, since they constitute an interruption [in the order of the blessings]. Rem"a: And there are those who say that there is no prohibition regarding this [Ri end of chapter "Ein Om'dim", and the Rashba, and the Tur], and such is the custom in all places to say them. But if one is lenient and does not say them, there is no loss. Nevertheless, one should not engage in any other activity. Even with words of Torah it is forbidden to interrupt and to engage in them the entire time the community is saying piyyutim - and all the more so is it forbidden to engage in any idle talk. However, one who studies merely by thinking, and simply looks at a book and thinks it over, there is nothing forbidden in that, since thought is not equivalent to speech. Even so, [this is not allowed] since through doing this, they may come to speak and would make an interruption. Therefore, one should not separate from the congregation in a place where they have the custom say them (piyyutim), and one should say them along with them. And see below Siman 90, Se'if 10 [Maharil and DA(?)].