When Yom Tov falls before Shabbat, one is required to prepare an Eruv Tavshilin before Yom Tov to allow him to cook on Yom Tov for Shabbat. If one came to the synagogue before Yom Tov and remembered that he had not prepared the Eruv Tavshilin, what options does he have so that he can be allowed to cook on Yom Tov for Shabbat?
If sufficient time remains before the onset of Yom Tov for him to return home and prepare the Eruv Tavshilin, he must certainly do so. But if one does not have enough time to return home, may he designate in the synagogue food that he has in his house as the Eruv Tavshilin? For example, if he knows that he has a boiled egg in his refrigerator and a loaf of bread in his pantry, can he designate them as his Eruv Tavshilin even though he is in the synagogue, and the foods are elsewhere?
The Chid"a (Rav Chayim Yosef David Azulai, Israel, 1724-1806), in his work of responsa Chayim Sha'al (1:9), addresses this question and rules that one cannot designate food that is not in front of him as an Eruv Tavshilin. Therefore, if the individual cannot return home in time before the onset of Yom Tov, he does not have the option of preparing the Eruv Tavshilin in the synagogue.
By contrast, Chacham Bentzion Abba Shaul (Or Le'tziyon, vol. 3, 22:7) and Chacham Ovadia Yosef (cited in Yalkut Yosef, vol. 5, p. 499) rule, however, that under extenuating circumstances one may, in fact, prepare an Eruv Tavshilin with food that is not in front of him. Therefore, if the person cannot return home in time to prepare the Eruv Tavshilin there, he may do so in the synagogue, having in mind the specific foods he designates as the Eruv. In such a case, though, one does not recite the Beracha "Al Mitzvat Eruv," and he must also omit the first two words of the standard text used for designating an Eruv Tavshilin – "Be'dein Eruva" being that the Eruv is not in front of him.
Summary: If one remembers after coming to the synagogue before Yom Tov that he had not prepared an Eruv Tavshilin, he must return home to prepare the Eruv. If there is not enough time remaining before Yom Tov to return home, then he may rely on those views allowing one to designate foods as an Eruv Tavshilin even if they are in a different location. In this case he omits the Beracha as well as the words "Be'dein Eruva."
