Good morning, everyone. This morning, we will discuss the halakha (Jewish law) of Eruv Tavshilin (joining of cooked foods). As we all know, the Torah permits cooking on Yom Tov (holiday) and preparing food on Yom Tov for that day itself, unlike on Shabbat, when one is not allowed to cook or prepare food for that day. On Yom Tov, the Torah says that food preparation—baking and cooking—is mutar (permitted) on Yom Tov for the day. However, one is not allowed to prepare or cook food on Yom Tov for the following day, whether the following day is a weekday or another holiday, as when we celebrate two days of Yom Tov. Either way, one would not be allowed to cook and prepare food for the following day, only for the day itself.
Now, what happens if we have a Friday Yom Tov, whether it is the first day of Yom Tov or the second day, and the following day is Shabbat? Is one allowed to cook and prepare food on Friday Yom Tov for Shabbat? The halakha is that we are not allowed to prepare or cook food unless we make an arrangement. If the holiday starts on Thursday, we would do this on Wednesday, and this basically means that we start cooking before the holiday and finish cooking on Friday. That is the only way we would be allowed to cook on Friday and prepare food for Shabbat, as long as we started and made this arrangement before the holiday began.
The rabbis made this halakha, this issur (prohibition), this takana (rabbinic enactment), in order to stress to us that the only reason we are letting you cook is because it is for Shabbat. Do not make the mistake of thinking that because I am allowing you to cook on Friday for Shabbat, one can cook on Thursday Yom Tov for Friday. That is a mistake. So, in order not to make such a mistake, the rabbis said, “We will only allow you to cook” if you made an Eruv (joining) beforehand. This way, one knows that it is not just a blanket heter (permission) allowing one to cook on Yom Tov. It is only because one started with the Eruv. And this Eruv only works from Friday till Saturday. Now we all know clearly that otherwise one would not be allowed to cook on Yom Tov. That is the reason for Eruv Tavshilin.
Now, we have to understand that, according to what we just explained, it must be that from the Torah it is permissible to cook on Friday for Shabbat. The rabbis said, “Okay, but we are not going to let you do it unless you make an Eruv,” so that you do not make a mistake about a different day. Because if it were prohibited by the Torah to cook on Friday for Shabbat, there would be no possibility of the rabbis coming in and making a takana to start with the Eruv and then continue cooking on Friday. If that were the case—if it were not permissible according to the Torah—there would be no way to fix that. So it must be that, according to the Torah, it is really permissible to cook on Friday. The rabbis do not want us to do it in order that we should not confuse things.
But why is it permissible to cook on Friday for Shabbat? Here we have a few opinions in Gemara, Masechet Pesachim. One opinion says, “Tzorchei Shabbat Na'asin B'Yom Tov”; Rav Chisda says that the Torah allows the needs of Shabbat to be done on Yom Tov as well. This means that even though we said the Torah allows cooking on Yom Tov only for that day itself, Shabbat is also included because Yom Tov and Shabbat are like the same holy days. Therefore, one would be allowed to prepare and cook food from Yom Tov to Shabbat for Shabbat, the same way one is allowed to prepare food on Yom Tov for that day itself. That is Rav Chisda’s reason.
According to Rabbah, the reason why it is not forbidden to cook on Friday for Shabbat is a rule, a concept called Ho'il: since guests unexpectedly might come on Friday, you would be able to serve them this food, and in fact you would be able to cook for them if guests were coming to you. So even though one was cooking for Shabbat, the fact that guests could come and one would be allowed to cook for them means that it is not prohibited by the Torah. The Torah views this food as if it is being cooked for those unexpected guests. Therefore, even though one had in mind to cook for Shabbat, it would not be a Torah prohibition.
So according to both Rabbah and Rav Chisda, we see that it is permissible from the Torah to cook on Friday for Shabbat. Then the rabbis stepped in and said that we are not going to allow it unless you make an Eruv Tavshilin. A practical halakha difference comes out of this machloket (dispute) about why it is permissible to cook on Friday for Shabbat. According to Rav Chisda, who says that you are allowed to do the needs of Shabbat on Yom Tov, one would be allowed to cook all day long on Friday using the Eruv. That means one would be able to cook toward the end of Yom Tov, toward the end of Friday, and the food would be ready only on Shabbat. That is still okay, because you are allowed to cook on Friday for Shabbat. And you made an Eruv, so you are good.
But according to Rabbah, if the whole reason why we are allowed to cook on Friday for Shabbat is this concept of guests possibly coming, this concept would not apply if one prepared the food very late on Friday afternoon and it was not going to be ready until Shabbat. We would not be able to use the rule that guests might unexpectedly come, because even if they came on Yom Tov, the food would not be ready for them. So now it turns out that we are cooking food on Yom Tov strictly for Shabbat. According to Rabbah, that would be no good; it would be asur (forbidden). The only reason why I allowed you to cook for Shabbat is because you might use the food on Yom Tov for unexpected guests. But if you do it in a way that the guests cannot have it, because it is not going to be ready by then, you would not be allowed to cook. And if you would not be allowed to cook, then it would be asur from the Torah, and the Eruv would not help. So according to Rabbah, one would not be allowed to cook late on Friday, even if one made an Eruv, with the food ready only on Shabbat. The Eruv is not going to help with that cooking. You would have to cook earlier in the day, and the food would have to be ready on Yom Tov itself. Then the Eruv would allow it.
Therefore, the Mishnah Berurah as well as Chazon Ovadia write that one should lechatchila (preferably) cook early on Friday and should not cook so late that the food will not be ready until Shabbat. One should cook the food so that it will be ready before Shabbat begins. This way, we have both Rav Chisda and Rabbah on our side, and according to everyone, the Eruv helps. If one prepared it late, we would lose the opinion of Rabbah. Therefore, one should be careful to do it early. If one gets busy and cannot do it for some reason, then the poskim (halachic authorities) allow one to cook, and we can rely on the opinion of Rav Chisda and still cook late. But preferably one should not do that.
Another point to make is that the Eruv, let’s say the holiday is on Thursday and Friday, followed by Shabbat, only helps a person cook on Friday for Shabbat. It would not help a person cook on Thursday for Shabbat. The Eruv only helps for the day before Shabbat, which is Friday. Also, just a simple point: when we say Friday, Thursday night is included. This means one would be allowed to cook and prepare for Shabbat on Thursday night, because that is already considered Friday.