Rosh Hashanah - Eruv Tavshilin

 A fundamental difference between Yom Tov (festival) observance and Shabbos (Sabbath) observance is the allowance of food preparation on Yom Tov. 

The Torah permits us to cook, bake, and prepare food on Yom Tov proper, in order to eat the prepared food on that day of Yom Tov. One is not permitted to prepare from one day of Yom Tov for the second day of Yom Tov or for after Yom Tov. 

This prohibition of preparing from one day of Yom Tov to the next, presents a problem when the second day of Yom Tov falls out on Shabbos or when Shabbos follows a two day sequence of Yom Tov. Can one halachically prepare food on Yom Tov for the Shabbos Yom Tov or for Shabbos?

To deal with this issue our Rabbis instituted a procedure known as eruv tavshilin. The process of eruv tavshilin works in the following manner. On Erev (the eve of) Yom Tov, the head of the household, or his designee, should set aside a baked item such as bread or matzoh, and a cooked item such as meat, fish, or eggs (i.e. a food that is eaten along with bread). He or she should then recite the blessing:

 בָּרוּךְ אַתָּה ה' אֱלקֵינוּ מֶלֶךְ הָעוֹלָם אֲשֶׁר קִדְּשָׁנוּ בְּמִצְוֹתָיו וְצִוָּנוּ עַל מִצְוַת עֵרוּב

Baruch Atah Adonai, Eloheinu Melach HaOlam, Asher Kidishanu B`Mitzvotov, Vitzivanu, Al Mitzvat Eruv  

 One continues with the following, which must be said in a language one understands:

בַּהֲדֵין עֵרוּבָא יְהֵא שָׁרֵא לָנָא לַאֲפוּיֵי, וּלְבַשּׁוּלֵי, וּלְאַטְמוּנֵי, וּלְאַדְלוּקֵי שְׁרָגָא, וּלִמֶעְבֵּד כָּל צָרְכָּנָא מִיּוֹמָא טָבָא לְשַׁבְּתָא

"With this Eruv we are permitted to bake, cook, keep things warm and light fire and do all that is needed from Yom Tov to Shabbat".

 This proclamation states that the cooked and baked items should permit us to continue baking, cooking, lighting a flame from an existing fire and do all the necessary preparations from Yom Tov proper to Shabbos. It is now viewed as though meal preparations for Shabbos have already begun before Yom Tov and Shabbos meal preparations may continue on Friday Yom Tov, Erev Shabbos.

Once done, the eruv covers all household members and guests.

The foods set aside for the eruv should be saved and may be eaten on Shabbos but not prior to Shabbos..

If one forgot to make an eruv tavshilin one should consult a competent Rabbinical authority for further instructions.