Don’t forget to make an Eruv Tavshilin this year on Thursday, 12 April. Please cut this page out and hang it on your wall or fridge to remind you to perform the Eruv. In order to avoid forgetting one may even make the Eruv on Tuesday night as well.
The prohibition against the performance of labor on the Festivals (Exodus 12:16) specifically excludes preparation of food. Still, it is forbidden to prepare food on a festival for use on another day. When a Festival falls on Friday, however it is permitted to prepare food needed for the Sabbath.
Nevertheless, to prevent the impression that one may cook on a Festival even for a weekday, the Rabbis attached a condition to preparation of Sabbath meals on a Fesival - i.e; such preparations may not be made unless they were begun before the Fesival (Pesachim 46b). In other words, if a Festival falls on Friday, preparations for the Sabbath meal must begin on Thursday (Wednesday, if a festival is on Thursday and Friday). This enactment is called eruv tavshilin, literally, mingling of cooked foods, and consists of a matzah, along with any other cooked food (such as fish, meat or an egg). These are set aside on the day before the Festival to be eaten on the Sabbath. The eruv foods are held in the hand (Orach Chaim 527:2) and a blessing is recited. Since the person setting the eruv must understand its purpose, the accompanying declaration must be said in a language he understands.
The food is handed to another member of the Household other than the person making the Eruv. The one making the Eruvrecites.....
I hereby grant a share in this Eruv to anyone, who wished to participate in it and to depend upon it.
The one to whom the Eruv food was handed raises them a tefach (handsbreadth) and then returns them to the one making the Eruv, who recites the following blessing and formula:
ברוך אתה ה' אלקינו מלך העולם אשר קדשנו במצותיו וצונו על מצות ערוב
Blessed are You, Lord our G-d, King of the universe, who has sanctified us with His commandments, and commanded us concerning the Mitzvah of the Eruv.
Through this it shall be permissible for us to bake, cook, to put away (a dish to preserve its heat), to kindle a light, and to prepare and do on the Festival all that is necessary for the Shabbat - for us and for all Israelites who dwell in this city.