Siman 413

One who establishes an eruv for the public from his own property says: "Behold, this eruv is for all the residents of the city," provided that there is the food of two meals for each person. This is not similar to eruvei chatzerot, where two meals suffice for everyone even for a thousand people, as written in siman 365, for there they restrict one another and we make them as if they are merged—two meals are enough. But here, each person's dwelling is for himself, and therefore two meals are required for each person (Taz); and furthermore, techumin is more stringent as they supported it with a verse (Eliyah Rabbah). And even though regarding bread they were lenient, it seems to me that this is because in techumin the essence of the eruv is by foot, and therefore it is impossible to say bread specifically. And it further seems to me a simple reason, that in techumin, since one uproots his dwelling from his entire house, his courtyard, and his city to a completely different place—therefore we require two meals for each person. And when he places it for all the residents of the city—he must grant them merit through another person, as in eruvei chatzerot in siman 366.

And also in this, it is not similar to eruvei chatzerot and meva'ot, where one may establish the eruv without their knowledge, but regarding techumin—it is only with knowledge, for there is not only a benefit here, but there is also a disadvantage, as he loses the other side, as has been explained. Therefore, one who establishes an eruv for an individual or for many—must inform them while it is still day. However, for anyone whom he informed while it was still day, even if he did not resolve in his heart until it grew dark—it is a valid eruv, for regarding techumin we say breira, that the matter is clarified retroactively that he acquired his place of rest at the location of the eruv. But when they did not inform him at all while it was still day, upon what would the breira take effect, for he did not know of the eruv at all.

And so too, one who placed an eruv for all the shabbatot of the year, and said, "On whichever of the shabbatot I desire, I will go and rely upon it," even though at bein hashemashot he had not resolved in his heart until the next day—he may rely upon it, due to the principle of bereirah that we explained. And so too, one who heard that a certain sage is coming on Shabbat, but did not know from which direction he will come, and placed two eruvin and said: "If the sage comes to the east—my eruv is to the east; and if to the west—my eruv is to the west; and if two sages come, one from here and one from here—to the place I desire I shall go; and if he comes neither here nor there—behold I am like the residents of my city"—he may do so, and his eruv is an eruv. And also on the next day he may choose, if two come, one from here and one from here, to whichever side he desires, and all is due to the principle of bereirah, and all is according to his condition. And so too, if he said to two or to three: "Behold I am making an eruv for whichever of you I desire tomorrow," or if he said plainly: "for whichever of you I desire," and did not clarify whom he desired until it became dark—it is an eruv, and all is due to the principle of bereirah as we have written.