The Timing of Pidyon Ha-Ben
As noted above, the Torah writes that the mitzvah of Pidyon Ha-Ben is to redeem a firstborn son when he turns a month old. The question, however, is to which month is the Torah referring?
Although all Jewish calendar months are either 29 or 30 days long (corresponding to whether there are one or two days of Rosh Chodesh), these are actually results of a calendar whose units are complete days. There is a dispute among authorities as to whether the duration of the month for Pidyon Ha-Ben is based on complete days too, or whether the Pidyon Ha-Ben month has a higher resolution.
According to the Magen Avraham (339:8) and many others, the duration of the Pidyon Ha-Ben month is measured in complete days, and therefore a Pidyon Ha-Benshould take place on the 31st day after a firstborn boy is born. A day in this context refers to a day as it is defined in virtually all areas of halachah, as beginning and ending at sundown (the day follows the night). According to this opinion, the thirty-one day count includes the day of birth, and therefore the first day is considered to have passed at the first sunset after the birth, even if this is just minutes after delivery. According to this opinion, there is no need to take into account the astronomical month, and as soon as thirty halachic days pass one can perform the Pidyon.
According to the Shach (Yoreh De'ah 305:12), however, the duration of a month for Pidyon Ha-Ben is determined by the the time that transpires from one new moon to the next. Since the time that transpires from one new moon to the next is 29 days, 12 hours and 793/1080 of an hour (usually called 793 chalakim), the time for Pidyon Ha-Ben begins when the firstborn child is exactly 29 days, 12 hours and 793 chalakim old (Shach, Yoreh De'ah 305:12).
It is noteworthy that a third opinion, raised by the Oneg Yom-Tov, suggests that the minimum time is thirty complete twenty-four hour periods (meaning, 720 hours). This opinion is close to the foregoing opinion of the Shach, and it is not broadly cited.
The common Ashkenazi practice, which is based on rulings of the Peri Megadim (as cited by the Pischei Teshuvah 305:17), the Noda Biyhuda (Tinyana 187), Rabbi Akiva Eiger (Tinyana 22), and others, is to take both opinions into account, and to delay the fulfillment of the mitzvah until both periods have elapsed. Some authorities write that there is no requirement to be concerned about the astronomical month opinion, and it is sufficient to wait until thirty calendar days pass (see Birchei Yosef 305:14; Maharam Schick Yoreh De'ah 302:3). This is the common Sephardi custom.
Certainly, one cannot be lenient based on the Shach (the astronomical duration), since the great majority of authorities do not concur with his calculation (see Otzar Pidyon Ha-Ben 15:2).
Pidyon Ha-Ben in the Afternoon
Usually, by the morning of the 31st day, the firstborn has already reached 29 days, 12 hours and 793 chalakim. However, if the infant was born shortly before sunset on a long summer day (on long summer days the daylight hours are very long and the nights are short), daybreak on the morning of the 31st day is less than 29 days, 12 hours and 793 chalakim since his birth.
In this situation, one should wait to perform the Pidyon until the baby is at least 29 days, 12 hours and 793 chalakim after birth (Pischei Teshuvah, Yoreh De'ah 305:17).
For this reason, it is a common custom to schedule a Pidyon Ha-Ben on the afternoon of the 31st day, which is always an appropriate time according to both opinions.
When the earliest time to perform the Pidyon is on an Erev Shabbos or Yom Tov, the Pidyon should be scheduled in the morning (Mishnah Berurah 249:13). The reason for this is that one may not eat a festive meal in the afternoon preceding Shabbos or Yom Tov, because this will diminish from the honor of the Shabbos or Yom Tov meals.
Pidyon Ha-Ben at Night
Can a Pidyon Ha-Ben be performed at night? There does not appear to be any reason for a Pidyon not to be performed at night. Moreover, the Gemara (Kiddushin 34a) writes that Pidyon Ha-Ben is not a time-bound mitzvah, which clearly implies that the Pidyon can be performed at night.
Yet, the Shach (305:12), though agreeing that according to the Talmudic halachah there is no problem with performing a Pidyon at night, writes that the custom is to refrain from doing so. Several explanations are given for this fairly universal (among Ashkenazim – see Pidyon Ha-Ben Kehilchato 6:7) custom.
The Noda Biyhuda explains the custom based on the requirement to fulfill both opinions concerning the timing of the Torah month. Because of the likelihood that the night of the 31st day arrives before the passing of an astronomical month, it is the custom to avoid performing the Pidyon on the night of the 31st (see Dagul Mervava on Magen Avraham 568:10).
An alternative explanation is given by the Shaarei Teshuvah (568:8), who writes that the reason we perform the Pidyon during the day is in order to better publicize the mitzvah. This rationale is noted by a number of additional authorities (see Mateh Efraim, Elef Le-Mateh 581:27; Netziv, Meishiv Davar 2:85) – though this reason may be less applicable today, when people are more available to take part in such mitzvah events at night than they are during the day.
Aside from these considerations, a number of sources suggest other, more spiritual or esoteric reasons for why the Pidyon should not be performed at night (see Pidyon Ha-ben Kehilchato 6:23). For instance, the anonymous author of Seder Pidyon Ha-Ben Le-echad Me-chakhmei Ashkenaz (printed in Moriah, Vol. 11) forbids a nighttime Pidyondue to the firstborn's status as kodashim – sacred property of the Temple – that the child retains until the redemption. Just as one may not redeem Temple property at night, so one may not redeem his firstborn after dark.
When the Thirty-First Falls on Monday
If a baby boy is born on Shabbos, the thirty-first day will fall on Monday. This often raises the issue of when to perform the Pidyon Ha-Ben: On the one hand, the customary time for the Pidyon is on Monday afternoon, as we have noted. Yet on the other hand, many (in particular those who live where Sunday is not a working day) prefer to perform the Pidyon on Sunday night, which would allow more people to attend.
Is it permitted to perform the Pidyon on Sunday night, thereby publicizing the event before a greater audience, or must it wait until Monday?
Based on the mainstream approach of the Shaarei Teshuvah and others, according to which the reason for the general custom is so more people will attend, there is room to contend that in this case, where arranging the Pidyon at night will permit greater attendance, the Pidyon should indeed be performed at night.
Even according to the rationale given by the Noda Biyhuda, some suggest that the custom of performing the Pidyon in the day only applies where the period of an astronomic month has not yet elapsed; once the astronomic month has also elapsed since birth, the custom of delaying the Pidyon until the day will not apply (see Shut Etan Aryeh no. 31). The reason for the custom, according to this approach, is a concern that the required time has not elapsed. Where it is certain that the required time has elapsed, the Pidyon can be performed at night.
There two further reasons to argue that the custom of waiting until the evening of the thirty-first day can be waived.
First, we find that Shut Yehudah Ya'aleh (Vol. 1, Yoreh De'ah 262) questions the validity of the custom, and writes that based on the principle of not delaying the fulfillment of mitzvos (which is noted by the Shulchan Aruch 305:11 with regard to Pidyon Ha-Ben), one should in fact perform the Pidyon right away on the night after the thirtieth day. Among Ashkenazi authorities, however, this is very much a minority position.
Second, the Netziv (Meishiv Davar, loc. cit.) writes that the custom is not binding, and is left to the discretion of the parent. Rav Yaakov Emden, though encouraging adherence to the custom, also writes that it may be waived for any reasonable cause (Migdal Oz, Birkos Horai 3:7).
Therefore, there is certainly some room to bring a Monday Pidyon forward to Sunday night. For specific cases a halachic authority should be consulted.
When the Thirty-First Falls on Shabbos
If a baby is born on Thursday, the thirty-first day will fall on Shabbos. A Pidyon is not performed on Shabbos, because the act of the Pidyon resembles commerce (which is forbidden on Shabbos), and therefore the Pidyon is delayed until after Shabbos.
Under these circumstances, the Noda Biyhuda himself rules that the Pidyon should take place on the night of the thirty-second – meaning on Motza'ei Shabbos.
According to the Noda Biyhuda, the custom of delaying the ritual to the daytime is the concern that the required period of time may not have passed by the night of the thirty-first day. Therefore, when the thirty-first day occurs on Shabbos, and parents must choose between Motza'ei Shabbos (the night of the thirty-second day) and Sunday, they should adopt the former option. Since the required period of time has certainly passed by the night of the thirty-second day from birth, the custom of not performing a pidyon ha-ben at night no longer applies.
The author of Otzar Pidyon Haben (17:2) even claims that the general custom under such circumstances is to perform the Pidyon on Motza'ei Shabbos.
It is worth noting that although one must generally be very wary of delaying mitzvah performance, with regard to a Pidyon Ha-Ben that was delayed for a legitimate reason (such as if the thirty-first day fell on Shabbos), there is no further prohibition in delaying the Pidyon longer (Magen Avraham 568:10).
Delaying the Pidyon to a Different Day
Although we have seen that there may be grounds to perform a Pidyon ceremony early, on Sunday night, out of consideration for the publicity of the mitzvah, it is certainly wrong to delay the fulfillment of the mitzvah beyond the thirty-first day for the sole purpose of publicizing the mitzvah.
Rav Moshe Feinstein (Iggros Moshe, Yoreh De'ah Vol. 2, no. 118) addresses this question, and answers in clear terms:
"In a case of Pidyon Ha-Ben where the thirty-first day occurs during the middle of the week and the father wants to delay the ceremony until Sunday so that he can hold a more elaborate celebratory meal, it is clear that one should not do so, so as not to delay the mitzvah. Even though during the week there will not be many people who will attend, one should not delay it so more can be present. ... Therefore, it is proper to make the ceremony at its proper time even if the attendance is small."
Notwithstanding this clear-cut statement, Rav Moshe adds:
"However, if the father refuses to do the ceremony before Sunday, it can be held on that date and the mitzvah will have been accomplished just as if it were held at its proper time. Pidyon Ha-Ben at its proper time is important so as not to delay the mitzvah, but one does not transgress the commandment (if it is delayed)."
Thus, it is wrong for a person to delay the fulfillment of the mitzvah, even for the purpose of augmenting the number of attendees. Yet, if he does delay the Pidyon the mitzvah is fulfilled and no commandment is transgressed.
If the thirty-first day falls on a fast day, it is legitimate to delay the Pidyon until the night of the thirty-second, when the Pidyon may be performed during the festive meal, as customary (Shach 305:12). Another option is to perform the Pidyon on the fast day, and to postpone the meal until after nightfall – though the Shach comments that this practice will certainly lessen the publicity of the mitzvah.