Laws of Kedusha
One of the reasons we pray together as a congregation is in order to sanctify
There exist several different formulas (nuschaot) for the Kedusha prayer. Sefardim and Chassidim, praying a similar nusach that follows in general the instructions of the Arizal, begin with “Nakdishach vena’aritzach”. Nusach Ashkenaz begins with “Nekadesh es shimcha”. Though there are differences in the opening and closing of the Kedusha prayer, its essential part is the same for everyone. All answer in unison to the congregation leader with the following three verses: 1) “Kadosh, kadosh, kadosh, A-do-noi Tze-va-ot, melo kol ha’aretz kevodo” ― Holy, holy, holy is
The Kedusha prayer is of utmost importance. As such, the Rabbis permit interrupting one’s own prayers in order to join together with the congregation for its recital. Before Baruch She’amar one can say the entire Kedusha, even the parts that the congregation leader says. If one is in the middle of Pesukei DeZimra one may interrupt only to say the three verses of Kedusha. He can also say the verse Yimloch, since many authorities consider it part of the essential Kedusha prayer. If, however, one is in the middle of the Shema or its blessings, he interrupts only for the first two verses, since there are poskim that do not consider the third verse Yimloch as part of the essential Kedusha prayer. Even during the Shemoneh Esrei, when one cannot interrupt at all, one should pause and listen to the Kedusha, and afterwards resume the Shemonah Esrei (Piskei Teshuvot).