시편 25:6 할라카: Shulchan Arukh, Orach Chayim

Laws of the Congregation's responding to the Kaddish (5 sections): One should have concentration when answering the Kaddish. Rem"a: And one does not interrupt between "Y'hei Sh'meih Rabbah" ("May the Great Name") and "M'varakh" ("be blessed") [Hagahot Asheri in the name of Or Zarua wrote regarding the first explanation: "One should not interrupt between "Sh'meih" and "Rabbah" and according to the explanation of the Ri: one should not interrupt between "Rabbah" and "M'varakh"]. and one should answer loudly and strive to run to hear Kaddish. Rem"a: And one should stand when answering Kaddish and any davar she-bikdushah ("matter in which there is holiness" - a recitation which requires a minyan). And one who comes to synagogue and hears the congregation answering Kaddish answers along with them even though he did not hear the prayer-leader saying "Yitgadal etc." [Hagahot Chadashim on the Mordechai on Brakhot]. And the prayer-leader also needs to say "Y'hei Sh'meih Rabbah...". And when he begins "Yitgadal...", one should say "And now, let power [of YHVH] be magnified..." (Numbers 14:17) and "Remember Your mercy..." (Psalms 25:6).