Av Harachaim on Shabbos Mivarchim Sivan and on Shabbos before Shavuos:[1]

Av Harachamim is recited on Shabbos Mivarchim Sivan.[2]

Saying Av Harachamim if a Baal Bris or Chasan is in Shul, and by Shabbos before Shavuos:[3]  Even in the event that a Bris is taking place in Shul [or if there is a Chasan in Shul] on Shabbos Mivarchim Sivan, as well as on remaining Shabbosim within the days of Sefira[4], Av Harachamim is to be recited. [Accordingly, it is also to be recited during Shabbos of the Shloshes Yimei Hagbalah, and even on Shabbos which is Erev Shavuos, even though Tachanun is omitted on these days.[5] However, based on the ruling of Admur in the Siddur[6], some Poskim[7] rule that Av Harachamim is to be omitted in the presence of a Chasan or Bris even on Shabbos Mivarchim Sivan, and the same would apply regarding any Shabbos in which Tachanun is omitted, which is all the Shabbosim between the 1st of Sivan and Shavuos.[8] Other Poskim[9], however, learn that even according to the Siddur it is to be recited even in the event that a Bris is taking place in Shul or a Chasan is present in Shul. Practically, the accepted approach is like the former opinion to omit Av Harachamim on any Shabbos that Tachanun is not recited even during Sefira.]

Vihi Noam:[12] When Yom Tov falls on a weekday, including if it falls on Erev Shabbos, the entire[13] prayer of Vihi Noam is customarily omitted on the Motzei Shabbos directly prior to the Holiday.[14] Thus, on the Motzei Shabbos which precedes Shavuos, Vihi Noam is omitted.

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[1] Admur 284:14; Rama 284:7; Admur in Siddur

Shabbos Mevarchim Iyar: On Shabbos Mivarchim Iyar, Av Harachamim is omitted as we do not say Tachanun in the month of Nissan. [Implication of Admur in Siddur who omits Iyar; Admur 429:8 in parentheses; Ketzos Hashulchan 83 footnote 13; Piskei Hasiddur 133; Siddur Maharik, brought in Hagahos of Rebbe; Beir Hagoleh 284 in name of Maharshal; Siddur Kol Yaakov] In the Shulchan Aruch ibid, Admur rules that it is to be recited also on Shabbos Mevarchim Rosh Chodesh Iyar, and so is the ruling of the M”A 284:8.

Shabbasos during Sefiras Haomer in end of month of Nissan, Iyar and beginning of Sivan: One is to recite Av Harachamim on all the Shabbasos of Sefirah, even if there is a reason to omit it, such as a Bris. [Admur 284:14; M”A 284:8] However, see next based on Admur in Siddur and 429:8 that it is to be omitted whenever Tachanun is omitted, and hence it is omitted by all Shabbosim of Nissan.

Isru Chag Pesach: In Eretz Yisrael in certain years Isru Chag of Pesach falls on Shabbos. Some Poskim rule that by such an occurrence, Av Harachamim is to be recited that Shabbos just like in the diaspora in which it is said due to Yizkor. [Koveitz Mibeis Levi 7:17] However, others write to omit it by Isru Chag of Pesach that falls on Shabbos in Eretz Yisrael. [Luach Eretz Yisrael Tukichinsky] According to Admur in his Siddur and ruling in 429:8, it is to be omitted.

[2] The reason: As terrible decrees occurred during this time period of Sefira and hence we recite this prayer. [Admur ibid; M”A ibid; See Hisvadyos 1983 p. 1448] This refers to the decrees of the year 4856, 1096, the first Crusades. [Machatzis Hashekel 284]

[3] Admur 284:14; M”A 284:8; M”B 284:18

[4] Admur ibid “Bashabbasos Haheim,” referring to days of Sefira. Now, if we recite Av Harachamim even on Shabbos Mevarchim of these months even when there is a Bris, then certainly it is to be recited by the other Shabbasos even if there is a Bris, or other reason to omit Tachanun.

[5] Shaarei Efraim 10:28; Nimuei Orach Chaim 284:3; Piskeiy Teshuvos 284:17

[6] That we omit Av Harachamim on Shabbos Mivarchim Iyar due to it being within the month of Nissan when Tachanun is omitted. [Siddur Admur does not list Iyar as one of the months to omit Av Harachamim; Ketzos Hashulchan ibid]

[7] Ketzos Hashulchan 83 footnote 13; Piskei Hasiddur 133; Hiskashrus 930 footnote 9

[8] Ketzos Hashulchan 83 footnote 13 “and not on any other Shabbos in which Tachanun is omitted”;

The reason: As Admur in the Siddur omitted the month of Iyar from his list of Shabbos Mevarchim months in which Av Harachamim is to be recited, unlike his ruling in the Shulchan Aruch. The assumed reason for this is because Tachanun is omitted in the month of Nissan, and hence from here we can learn that whenever we have another reason to omit Tachanun, then Av Harachamim is to be omitted even on Shabbos Mivarchim Sivan. [Shabbos Mivarchim Iyar]

[9] Kitzur Hilchos Shabbos Milluim p. 81; See Rav Raskin in his Siddur p. 311-312

[10] See Admur 284:14 that on Rosh Chodesh that falls on Shabbos we omit Av Harachamim even in Iyar Sivan, and hence we should apply the same thing regarding Erev Rosh Chodesh after Chatzos, even according to the ruling in his Shulchan Aruch, hence it is not relevant to the above debate

[11] Hisvadyus 1986 Parshas Bechukosaiy p. 366

[12] Admur 295:3

[13] Ata Kadosh: This omission includes also the prayer of Ata Kadosh. The reason it is accustomed to omit also Ata Kadosh is because the prayer of Ata Kadosh is said as a result of saying the prayer of Vihi Noam. As once the Shechina resides below, as is stated in the prayer of Vihi Noam which discusses the Mishkan, it is then fit to sanctify it with the prayer of Ata Kadosh. Thus, since Vihi Noam is omitted, [for the reason to be explained in the next footnote] so too we omit Ata Kadosh. [ibid]

Other Opinions: The above follows the Ashkenazi custom, as brought by the Tur. However, the Sefardi custom is to only omit Vihi Noam and Yosheiv Beseiser, and they thus begin from Orech Yamim, and then say Ata Kadosh. [Tur] Some however say the Sefaradi custom is to recite it entirely, as rule the Sefaradi sources brought in the next footnote. [Piskeiy Teshuvos 294:2]

[14] The reason: The reason for omitting Vihi Noam is because within the prayer we say twice “And the work of our hands”, and hence all the days of the coming week have to be fit for work. If they are not, then we omit the prayer. [Admur ibid; See Piskeiy Teshuvos 294:2 for a thorough analyses on this subject]

Other Opinions: Some, based on Kabala of Arizal, always recite the prayer of Vihi Noam on Motzei Shabbos, even when a Holiday falls that week, and even on Motzei Shabbos Chol Hamoed. Nevertheless, in such circumstances, they recite it quietly. Their reasoning is because Vihi Noam affects the influence of Shabbos on the weekday which is needed every week, without exception. [Birkeiy Yosef brought in Shaareiy Teshuvah 295:2; Kaf Hachaim 295:9-10]