12 October 2011

Eruv Tavshilin

Eruv Tavshilin (Chabad.org)

It is forbidden on a holiday to do any act in preparation for the following day,1 even if the following day is Shabbat. However, the sages created a halachic device, called an eruv tavshilin, which allows one to cook food on a holiday day for use on a Shabbat that immediately follows it.

If a holiday day -- whether the first or second day of a holiday -- falls on a Friday, an eruv tavshilin is set aside on the day preceding the holiday (Wednesday or Thursday afternoon), so that we will be permitted to prepare for Shabbat (cooking as well as any other necessary preparations) on the holiday. Only one eruv is required per household.
Link: Eruv Tavshilin