Question: How important is it for non-Kohanim to hear Birkas Kohanim, and how should the congregation conduct themselves during Birkas Kohanim to receive the blessings of the Kohanim?
Discussion: Many authorities maintain that, in addition to the mitzvah of the Kohanim to bless the Jewish people, non-Kohanim who listen to the Kohanim’s blessing also fulfill a mitzvah.27 Women are also included in this mitzvah.28 Accordingly, it is proper for non-Kohanim to make an effort to hear Birkas Kohanim at least once a day. As mentioned in the previous discussion, for Ashkenazim outside of Eretz Yisrael, this applies only on Yom Tov.
For the congregants to fulfill the mitzvah properly and avail themselves of the blessings of the Kohanim, they must position themselves so that they are facing the Kohanim (see further details below). They must give their undivided attention to the words of the blessings and must hear every single letter of every single word.29 They should not stare at anything that will cause them to lose concentration.30 The custom is for the entire congregation to stand with awe and seriousness during Birkas Kohanim.31 However, a weak or sick person may sit.32
One may not speak, learn Torah, or say Tehillim while the Kohanim are reciting the words of Birkas Kohanim.33 It is not proper to recite any verses, even those that appear in many siddurim, while Birkas Kohanim is taking place.34 One should not even respond to Kaddish, Kedushah, Barchu, or answer Amen to any berachah during Birkas Kohanim.35
In addition to responding Amen to the berachah of לְבָרֵךְ אֶת עַמּוֹ יִשְׂרָאֵל בְּאַהֲבָה recited by the Kohanim before Birkas Kohanim, the entire congregation must answer Amen to each of the three verses of blessing that the Kohanim recite.36 However, it is best for the chazzan not to respond Amen to the berachah of לְבָרֵךְ אֶת עַמּוֹ יִשְׂרָאֵל בְּאַהֲבָה.37 It is important to wait until the Kohanim finish enunciating the final word of each berachah before answering Amen.38 One who is present and does not answer Amen excludes himself from the berachah and does not fulfill the mitzvah.39
Some Poskim rule that it is proper for the congregation to respond baruch Hu u’varuch Shemo when hearing the Kohanim recite the Name of Hashem.40 However, others rule that one should not do so because it can cause confusion.41 One who wishes to respond baruch Hu u’varuch Shemo should do so quietly, unless the congregation’s custom is to respond.42
The custom is for the congregation to thank the Kohanim for their blessing by saying “yasher koach.”43 Many Kohanim respond to those thanking them by saying, “beruchim tihiyu” – you shall be blessed.44 Some authorities advise the Kohanim against responding with these words to avoid a possible halachic issue regarding whether such a response constitutes an additional blessing beyond what is proscribed by the Torah, and thus, a violation of bal tosif – adding on to the mitzvos of the Torah.45
27 This is the view of Sefer Chareidim (4:18) and other early authorities (see Nesias Kapayim Kehilchasah 1, footnote 58). It is quoted as halachah by many later authorities, including R’ Akiva Eiger 128:1, Sha’arei Teshuvah 128:2, Beiur Halachah (Introduction to Chapter 128) and Igros Moshe (Orach Chaim IV, 21:2). However, there are dissenting opinions. For instance, see Teshuvos Chasam Sofer (Orach Chaim, 167), who writes that the majority of Poskim maintain that there is no mitzvah to accept Birkas Kohanim. Aruch Hashulchan 128:4 writes that even if there is no Biblical mitzvah to accept Birkas Kohanim, “there is an obligation to be blessed by the Kohanim, and one who does not care to be blessed demonstrates a denigration of Hashem’s blessings and deserves to be punished.”
28 Minchas Chinuch (Mitzvah 378). Regardless, women and children are definitely included in the berachah of the Kohanim; see Mishnah Berurah 128, note 98. See also footnote 56 below. below.
29 Shulchan Aruch 128:23; Mishnah Berurah ibid., 65, 67. [ R’ S. Z. Auerbach (Halichos Shlomo, Tefillah 10:1) debates whether a person who misses one word fulfills the Biblical mitzvah that is incumbent on the congregation.]
30 Shulchan Aruch 128:23 with Mishnah Berurah 128, note 89.
31 Mishnah Berurah 128, note 51.
32 Tzitz Eliezer XIV:18; Yechaveh Da’as V:15.
33 Shulchan Aruch 128:26 with Ba’eir Heitev 46.
34 Mishnah Berurah 128, note 103.
35 R’ S. Z. Auerbach (Halichos Shlomo, Tefillah 10:4). R’ Auerbach (Devar Halachah 8) explains that this is because the Yerushalmi (Sotah 7b, cited by Tur 128) tells us that Hashem himself stands behind the Kohanim in concurrence with their blessing. Thus, it is as if He is speaking to the congregation and it is therefore not appropriate to interrupt even to respond to Kaddish. See Birkas Horai 11, footnote 56, for a dissenting opinion.
36 According to some, answering Amen to Birkas Kohanim is a Biblical obligation; see discussion in Nesias Kapayim Kehilchasah 15, footnote 3. [One may respond Amen to the verses of Birkas Kohanim in a voice louder or softer than that used by the Kohanim when reciting these verses (R’ Y. S. Elyashiv cited in Notrei Amen II, 9:4).]
37 Mishnah Berurah 128, note 71 with Sha’ar Hatziyun 62. He may respond Amen to the three verses provided that he is praying from a siddur and is sure that doing so will not confuse him, Mishnah Berurah ibid.
38 Shulchan Aruch 128:18 with Mishnah Berurah 69.
39 Igros Moshe, Orach Chaim II:31; see also Igros Moshe, Orach Chaim IV, 21:2.
40 Pri Chadash 128:13; Kaf Hachaim 128:87.
41 Eishel Avraham (Buczacz) 124; Igros Moshe, Orach Chaim, III, note 17
42 Devar Shmuel 295; Beis Baruch I, p. 150; Yechaveh Da’as 4:9.
43 Mateh Ephraim 592:11; Mishnah Berurah 128, note 60.
44 See Aruch Hashulchan 128:24.
45 Har Tzvi, Orach Chaim I:62 based on the view of Rambam cited in Beiur Halachah 128:27, s.v. Ve’im Hosif.