Hosting a meal:[1]

It is customary to serve a festive meal to those gathered on the night prior to the circumcision.[2] [The Mohel, Sandek, and friends and relatives are to be invited to this meal.[3] It is disputed amongst the Poskim as to whether this meal has the status of a Seudas Mitzvah.[4] Some are accustomed to sing and dance during this meal.[5] Practically, it is no longer widely customary to serve an actual meal by this gathering[6], although it is customary to serve light refreshments and Lechayim.[7]

Preparing a table of delicacies without eating:[8] It is, however, forbidden to follow the practice of some to prepare a table full of food the night before the Bris as a sign of good luck, and not eat any of it, as doing so transgresses the prohibition of Darkei Emori.

What is one to learn?[9] It is customary to read several sections from the Zohar, verses of Tanach[10], as printed in certain select Siddurim and available in certain Sefarim written on the Mitzvah of circumcision.[11] Each person who is present is to be honored with reading a section of the learning.[12] It is customary for those gathered to also recite verses of the Shema with the newborn child[13], and so was the custom of the elderly Chassidim.[14] Those present are to use the remainder of the time saying over words of Torah and retelling stories of Tzadikim throughout the night.[15]

Singing Zemiros:[16] Some are accustomed to sing Zemiros at the Wach Nacht gathering.

[1] Admur 640:14 “The meal that is eaten by the Yoledes (as was the custom in previous times)”; M”A 640:13; Shach Y.D. 178; Degula Merivava on Shach ibid that this meal is the intended Seduas Yeshua Haben brought in Tosafus Bava Kama 80a; Machzor Vitri; Orchos Chaim Hilchos Mila; Klalei Hamila based on Midrash Tanchuma Tazria; Toras Shalom of Rebbe Rashab p. 78 that so was done by his Wacht Nacht that all the guests who came to Lubavitch to participate in the Bris were served a meal on the night prior to circumcision; Bris Avos Kuntrus Leil Shimurim 1 in name of Zecher David 2; Shevach Habris 12:4 footnote 9 in length

[2] The reason: As the holiness of the Mitzvah begins to shine already on the night before the Bris, and hence this is commemorated with a festive meal. [Bris Avos ibid in name of Zecher David; See Admur 493:4; Chok Yaakov 493:8]

[3] M”A ibid in name of Nachals Shiva

[4] See Admur ibid from whom it is unclear as to whether this meal is also considered a Seudas Mitzvah; M”A ibid records a dispute in this matter [Nachalas Shiva holds it is a Seudas Mitzvah while others hold its not, and hence concludes to be stringent regarding a Neder]; P”M O.C. 444 M”Z 9 concludes that it is not considered a Seudas Mitzvah

[5] Beis Lechem Yehuda 265:1 “and on the night of the circumcision it is customary to dance and rejoice”

[6] See Admur ibid in parentheses “so was customary in previous generations”; Aruch Hashulchan 640:15 “we are not aware of this meal at all”; See Os Shalom 265:30

[7] Bris Avos ibid in name of Zecher Dovid ibid; Shevach Habris ibid

[8] Rama Y.D. 177:3; Shach 178:6; Gra; Rabbeinu Yerucham Nesiv 17:5; Shabbos 67b; See Encyclopedia Talmudit Vol. 4 Erech Bris Mila p. 247 footnotes 20-21

[9] Shevach Habris 12:3

[10] Chabad custom: It is unclear as to what is the Chabad custom regarding reading verses of Scripture [i.e. Tehillim] during the Wacht Nacht ceremony. In Kuntrus Chanoch Lanar p. 7 it states that so was done by the Wacht Nacht of the Rebbe Rashab, that his uncles who were the holy sons of the Tzemach Tzedek, and dozens of Chassidim, stayed awake throughout the night learning Torah and reciting sections of Scripture and the Zohar; Following this approach, the author of the Shevach Habris records a list of verses that is to be recited as part of the ceremony. However, according to Rav Yochanon Gurary, author of Bris Nasan, as per his inquiry by a number of elderly members of Anash, it is not our custom to say these verses with the exception to the verses brought in the Zohar. This is due to the general restriction against reciting Tehillim, and Torah Shebichsav at night. Rav Eli Landa Shlita responded to our inquiry [as to what we should practically do], that one should read all the verses, as writes Shevach Habris.

[11] See Sefer Bris Yitzchak; Siddur Yaavetz; Otzer Habris

[12] Mishmeres Shalom 18:1

[13] Minhagim Wormz 139; Makor Chaim Bachrach 239; Likkutei Maharich Seder Mila

The reason: The saying of the Shema has the power to banish evil forces, and is hence recited at night as part of the bedtime Shema, and so should be done prior to the circumcision. [Likkutei Maharich ibid; Shevach Habris ibid footnote 4]

[14] Shevach Habris ibid in name of Rav Groner

[15] Zochar Habris 3:18; Otzer Habris 3:7-11

[16] Zecher Dovid Mamar 1:30 in name of Mavor Yabok; See Beis Lechem Yehuda 265:1 “and on the night of the circumcision it is customary to dance and rejoice”