Scheduling a Berit Mila for a Baby Born on Shabbat or Yom Tov, or Right After Sundown on Ereb Shabbat or Ereb Yom Tob
An infant who is born on Shabbat is circumcised the next week, on Shabbat. Although inflicting a wound is generally forbidden on Shabbat, the Misva to circumcise a boy on his eighth day overrides this prohibition, and thus a Berit Mila is performed on Shabbat for a child born the previous Shabbat. The Talmud infers this rule from the verse, "U’bayom Ha’shemini Yimol" ("He shall be circumcised on the eighth day" – Vayikra 12:3). The word "U’bayom" alludes to the fact that the circumcision is performed on the eighth day even if that day is Shabbat.
It goes without saying that this applies to Yom Tob, as well. If an infant’s eighth day is Yom Tob, the Berit Mila is performed on that day.
However, if, for whatever reason, a child was not circumcised on his eighth day, such as if he was not deemed medically fit for the procedure on that day, then his circumcision does not override the Shabbat restrictions. A Berit Mila is performed on Shabbat – or Yom Tob – only if it is the child’s eighth day.
Furthermore, a Berit Mila may not be performed on Shabbat or Yom Tob in a situation of Safek ("doubt"), where it is uncertain whether that day is indeed is the eighth day. Such a situation arises in the case of a child born during "Ben Ha’shemashot" ("twilight") – the period immediately after sundown. One should consult his/her Rabbi for the exact time defining Ben Ha’shemashot as it is approximately 11-15 minutes after sundown depending on time of year and location. This period is treated by Halacha as a period of Safek, as it is uncertain whether it should be considered daytime or nighttime. Therefore, if a boy is born within twilight after sunset on Friday afternoon, he cannot be circumcised the next week on Shabbat. If the period of "Ben Ha’shemashot" should be considered daytime, then the child is considered to have been born on Friday, and so the Berit should take place the next Friday; and if this period should be considered nighttime, then the child is considered to have been born on Shabbat, and so the Berit should take place on Shabbat. Since we are uncertain of the classification of "Ben Ha’shemashot," in such a case the child cannot be circumcised the next Friday – because Friday might be the seventh day, and not the eighth day – and he also cannot be circumcised the next Shabbat – because Shabbat might be the ninth day, and a Berit can be performed on Shabbat only if it’s the eighth day. Therefore, in such a case, the Berit is delayed until Sunday.
Once again, this Halacha is relevant also to Yom Tob. If an infant is born during the 13.5-minute period after sundown on Wednesday afternoon, for example, and Yom Tob begins on Wednesday evening the next week, the child cannot be circumcised on Wednesday – which might be the seventh day – or on Thursday, which is Yom Tob – because it might be the ninth day, and a Berit Mila is not performed on Yom Tob unless it’s the eighth day. The circumcision would therefore have to be delayed until after Yom Tob.
In discussing the laws of Berit Mila (Yoreh De’a 266:8), the Shulhan Aruch applies this principle even to Yom Tob Sheni – the additional day of Yom Tob added in the Diaspora. One might have thought that since this additional day is observed only Mi’de’rabbanan – by force of Rabbinic enactment – the laws of Yom Tob should be overridden on this day in a situation of Safek. According to this rationale, if a child is born during "Ben Ha’shemashot" the week before the evening of Yom Tob Sheni, the circumcision should be held on Yom Tob Sheni. However, the Shuhan Aruch rules that this is not correct, and Yom Tob Sheni is treated no differently than the first day of Yom Tob in this regard. As such, a Berit Mila is not performed even on Yom Tob Sheni unless it is the child’s eighth day without any uncertainty.
In the case of a child who does require a Berit Mila on Yom Tob Sheni, an interesting question arises as to whether it is preferable to find an Israeli Mohel who is not observing Yom Tob that day. Meaning, if the Berit is being held in Israel, would it be permissible for a Mohel visiting from the United States – who is observing a second day of Yom Tob – to perform the Berit, or should it be performed specifically by an Israeli Mohel, for whom that day is not Yom Tob? Similarly, if a Berit is being performed on Yom Tob Sheni in the United States, is there a preference to have a visiting Israeli Mohel perform the Berit, since for him that day is not Yom Tob? Or is it equally acceptable for an American Mohel to perform the Berit?
The answer is that since performing a Berit on Shabbat or Yom Tob on the infant’s eighth day is a Misva, there is no preference at all on Yom Tob Sheni to an Israeli Mohel over an American Mohel. A child is circumcised on Yom Tob in such a case "’Le’chatehila" – on the optimal level of observance, not as a necessary means of accommodating an unfortunate situation. Therefore, when a child must be circumcised on Yom Tob Sheni, any Mohel may perform the Berit, and there is no preference to an Israeli Mohel over an American Mohel. It should be noted that Rabbi Eliyahu Shamah in his Macshere Mila records that this case once happened in Aleppo and the Rabbi of Aleppo circumcised a child on the second day of Yom Tob even though there was a Mohel from Israel present.
Summary: If a child’s eighth day falls on Shabbat or Yom Tob, the Berit is performed that day. If the child’s precise date of birth is uncertain – such as if he was born during the Ha’shemashot period after sundown, which we are uncertain whether to consider daytime or nighttime – then the Berit does not override Shabbat. Thus, if a child is born during this period Friday evening, the Berit is performed on Sunday the following week. This applies also to Yom Tob, and to Yom Tob Sheni – a circumcision is performed on that day only if it is known with certainty that that is the infant’s eighth day. When a Berit is performed on Yom Tob Sheni, there is no preference to having the circumcision performed by an Israeli Mohel who is not observing Yom Tob that day.