This principle is based on the following concept: Since an eruv t’chumin establishes a particular location as a person’s place for the Sabbath, only one such place can be established, and not two.
As the Maggid Mishneh mentions, this halachah is dependent on the concept that in cases of Rabbinic law, the principle of b’reirah applies. Thus, retroactively it is considered that at the. commencement of the Sabbath, the person had the intent of establishing an eruv in the direction that he was eventually required to proceed.
See Tzafenat Paneach (in his gloss on Hilchot Shabbat 27:l), who states that the Rambam considers the limits on travel on the holidays and on Yom Kippur as Rabbinic in origin. In support, he cites the Rambam’s statements in Hilchot Sanhedrin, Chapter 19, regarding the negative commandments punishable by lashing: “A person who goes beyond the [Sabbath] limits on the Sabbath, a person who performs a forbidden labor on a holiday.”
The liability incurred by the violator is somewhat different. A person who willfully performs any of the Sabbath labors is liable for execution, while one who violates a forbidden labor on Yom Kippur is liable only for karet. (See Hilchot Sh’vitat Asor 1:2.)
See Hilchot Sh’vitat Yom Tov 1:4, which states that since the prohibition against the forbidden labor of transferring articles was lifted on the holidays regarding the preparation of food, it was lifted entirely.
See Maggid Mishneh and the Mishnah Berurah 416:31, which mention opinions that see a benefit in the establishment of eruvin in courtyards on the holidays as well.
Although for a single Sabbath one may not establish eruvin in two opposite directions, this rule does not apply when the Sabbath and a holiday follow one another. The Sabbath and the holidays represent two different expressions of holiness (Eruvin 38b). Therefore, the location defined as one’s “place”—and thus an eruv established—for one does not necessarily apply regarding the other. Similarly, regarding the two days of the holidays observed in the diaspora: in essence, the holidays were to be observed for only one day. The observance of a second day was instituted only because of uncertainty regarding the calendar. Therefore, the two days are also considered to be separate entities.
This also involves a redefinition of one’s place. Instead of its being considered to be the location of the eruv, it is considered to be one’s home.
Since these two days were observed as a holiday even in Eretz Yisrael when the moon was sanctified on the basis of the testimony of witnesses (Hilchot Kiddush HaChodesh 5:7), they are considered to be a single expression of holiness. Eruvin 39b refers to them as "one long day," and the halachic requirements that apply to one day apply also to the other.
See the notes on Halachah 8 with regard to whether or not it is necessary for the eruv to remain in its place for both nights of the holiday.
The food deposited for the eruv must exist at beyn hash’mashot and be fit to eat. This is particularly important in the summer months, when it is possible that the eruv has become stale or has been eaten by vermin (Mishnah Berurah 416:9).
Ordinarily, a person must establish his eruv before nightfall. Nevertheless, since he made a stipulation beforehand, we rely on the principle of b'reirah, and we say that retroactively it is considered to be as if he decided to rely on the eruv before nightfall (Maggid Mishneh).
For other examples of the Rambam’s rulings concerning this matter, see Hilchot Sh’vitat Yom Tov 5:20, Hilchot Terumah 1:21, Hilchot Ma’aser 7:1, and Hilchot Ma’aser Sheni 4:15.
If the eruv is not accessible—even if it is present in its designated location—it is not acceptable, as stated in Chapter 6, Halachot 8 and 12.
The Maggid Mishneh explains that the removal of the eruv is merely a suggestion offered, lest a person leave the eruv in its place, and it be destroyed by vermin or the like. In a place where the eruv will surely be preserved, there is no point in removing it. Needless to say, on the Sabbath, when it is forbidden to carry, and it is forbidden to remove the eruv, this suggestion does not apply.
If one leaves the eruv in the designated place and there is a possibility that it will be destroyed, one is required to go to that place on the following day to check that it still exists (Mishnah Berurah 416:14).
The Be'ur Halachah 416 asks: Since it is possible to establish the eruv by walking to the designated location (as stated in the following halachah), of what value is it that the person carried the food with him? The Be'ur Halachah explains that in this instance, we are speaking about a person who has an agent establish the eruv for him. Therefore, it is necessary for him to use food.
The eruv must be deposited in the same location; otherwise, this is forbidden. Were one to change either the location (or the food used for the eruv), one would have been considered as either preparing on the Sabbath for a holiday, or on a holiday for the Sabbath (Shulchan Aruch, Orach Chayim 416:2).
There is no obligation to eat it. The Rambam’s intent is merely that from this time onward, there is no obligation that the eruv remain intact (Mishneh Berurah 416:15).
The Rambam’s statement implies that on Rosh HaShanah, it is necessary to establish an eruv only on the first night of the holiday. Even if the eruv is consumed before the beginning ofthe second day, it is acceptable, just as it would be acceptable for the entire Sabbath, even if it had been consumed after beyn hash’mashot.
The Ra’avad objects to this ruling. He maintains that the distinction of the two days of Rosh HaShanah as a single “extended” day applies only as a stringency, but not as a leniency. Therefore, the eruv established before the first night must remain in its place on the second night as well.
The Maggid Mishneh justifies the Rambam’s view, bringing supports that indicate that our Sages’ definition of these two days as “one long day” brings about a leniency as well as a stringency. The Mishnah Berurah 416:11 follows the Rambam’s ruling.
He may not establish the eruv by depositing food, for this would involve the performance of an activity on either the Sabbath or the holiday for the benefit of the other. As mentioned, it is forbidden to prepare on the Sabbath for a holiday or on a holiday for the Sabbath (Shulchan Aruch, Orach Chayim 416:2).
He may not make a verbal statement, for this would be considered to be preparation for the coming day (ibid.).
Since he uses the same loaf, he is not considered to be performing a new activity; this location had already been established as his “place,” and he is merely perpetuating the existing situation. If he brought a different loaf, it would be considered to be preparing for the coming day (ibid.).
According to the fixed calendar we follow at present, it is impossible for Yom Kippur to fall on either Sunday or Friday. (See Rosh HaShanah 20a.)
This expression implies a ruling for which the Rambam has no explicit source in the Talmud, but which he arrived at through a process of deduction.
Rabbi Akiva Eiger explains that this also implies a leniency. As indicated by the conclusion of Halachah 8, there is no need to establish an eruv on the second day.
The rationale is that all the prohibitions that apply on the Sabbath also apply on Yom Kippur (Maggid Mishneh).
In Halachah 5.
Note the gloss of the Sefer HaKovetz on Halachah 5, which discusses whether the law in this halachah applies only with regard to a holiday and a Sabbath that follow consecutively, or also with regard to the two days of a holiday that are observed in the diaspora. The Magen Avraham 416:3 rules that the restrictions apply with regard to the two days observed in the diaspora as well.
See Chapter 6, Halachah 4.
For it is forbidden to prepare for the Sabbath on a holiday.
In Hilchot Sh’vitat Yom Tov 6:14-15, when discussing the establishment of an eruv tavshilin and other similar matters, the Rambam states that in the present era, we may not make such a conditional arrangement. This leniency was granted only in the era when the establishment of the calendar was dependent on the testimony of witnesses, and the second day of a holiday was observed because of a doubt concerning the day on which the holiday should be celebrated. At present, there is no such doubt, and the second day is celebrated because of a Rabbinic decree requiring us to preserve the previous custom. (See Hilchot Kiddush HaChodesh 5:5.)
Other authorities (see the gloss of the Ra’avad on Hilchot. Sh’vitat Yom Tov) take issue with the Rambam on this point; it is their view that is accepted as halachah in the Shulchan Aruch (Orach Chayim 393:1).
Beitzah 17a explains why a distinction is made. By establishing an eruv t'chumin, a person designates a place as his home for the Sabbath, and our Sages would not permit this to be done on a holiday. In contrast, the establishment of an eruv chatzerot negates one's ownership. Therefore, greater leniency is shown.
Note the Birkei Yosef (Orach Chayim 528), which states that a blessing should not be recited.
The Mishnah Berurah 393:6 suggests using the same loaf of bread. Otherwise, it would be necessary to keep both loaves until the Sabbath.
