Talmud - Shabbat 39a שבת ל״ט א׳

Any salted food item that was already placed in hot water, i.e., cooked, before Shabbat, one may soak it in hot water even on Shabbat. And anything that was not placed in hot water before Shabbat, one may rinse it in hot water on Shabbat, but may not soak it, with the exception of old salted fish or the colias of the Spaniards [kolyas ha’ispanin] fish, for which rinsing with hot water itself is completion of the prohibited labor of cooking. Once it is rinsed in hot water, it does not require any additional cooking. The same is true with regard to an egg that was slightly cooked. Since it thereby becomes edible, one who brought it to that state has violated the prohibition of cooking. The Gemara sums up: Indeed, conclude from it that this is its meaning.

We also learned in the mishna according to the first tanna: And one may not wrap an egg in cloths that were heated by the sun in order to heat up the egg, and Rabbi Yosei permits doing so. And with regard to that which we learned in a mishna that one may place cooked food into a pit on Shabbat to protect it from the heat; and one may place good, potable water into bad, non-potable water so that it will cool; and one may put cold water out in the sun to heat it, the Gemara asks: Let us say that this mishna is in accordance with the opinion of Rabbi Yosei in our mishna and not the opinion of the Rabbis as represented by the first tanna in the mishna. The Rabbis prohibited heating food with the heat of the sun.

Rav Naḥman said: With regard to heating food in the sun itself, everyone agrees that one is permitted to place food in the sun to heat it, as it is certainly neither fire nor a typical form of cooking. Likewise, with derivatives of fire, i.e., objects that were heated by fire, everyone agrees that it is prohibited to heat food with them, as heating with them is tantamount to heating with fire itself. Where they argue is with regard to heating with derivatives of the sun, i.e., objects heated with the heat of the sun. This Sage, who represents the opinion of the Rabbis, holds that we issue a decree prohibiting a person to heat with derivatives of the sun due to derivatives of fire, which are prohibited. People have no way of knowing how the cooking vessel was heated. If the Sages permit the use of objects heated in the sun, people will come to permit use of objects heated by fire as well. And this Sage, Rabbi Yosei, holds that we do not issue a decree. Even though it is prohibited to heat with derivatives of fire, heating with derivatives of the sun is permitted.

We learned in the mishna: And one may not insulate it in sand or in road dust that was heated in the sun. The Gemara asks: And let Rabbi Yosei disagree with this halakha as well. If he holds that one is permitted to cook on Shabbat using objects heated by the sun, the same should apply with regard to sand. The Gemara cites two answers. Rabba said: Rabbi Yosei agrees with the opinion of the Rabbis in this case. The Sages issued a decree in this case due to concern lest one come to insulate it in hot ashes, which is certainly prohibited, if he is permitted to insulate food in sand or road dust. Insulating in sand and insulating in hot ashes appear to be very similar. Rav Yosef said: Rabbi Yosei prohibits it in this case because when insulating it in the sand, he displaces dirt. It is as if he dug a hole in the sand, which is prohibited. The Gemara asks: What is the practical difference between the answers proposed by Rabba and Rav Yosef? Apparently, the two answers lead to the same practical conclusion. The Gemara answers: There is a practical difference between them in the case of loose earth. Loose earth does not require digging a hole. According to Rav Yosef’s explanation, there is no reason to prohibit insulating food in loose earth, as displacing loose earth involves no prohibition. However, if the decree was issued lest one insulate an egg in hot ashes, then it applies even in the case of loose earth.

The Gemara raises an objection from that which was taught in a baraita: Rabban Shimon ben Gamliel says: One may slightly roast an egg on a hot rooftop heated by the sun; however, one may not slightly roast an egg on top of boiling limestone. Granted, this works out well according to the opinion of the one who said that insulating an egg in sand is prohibited due to a decree lest he come insulate it in hot ashes. There is no reason to issue a decree on a hot rooftop, as it is not at all similar to hot ashes. However, according to the opinion of the one who said that the reason is because he is displacing dirt, let him issue a decree and prohibit warming an egg on the rooftop as well because there is sometimes dirt on the roof. The Gemara answers: This is not difficult because, in general, a rooftop does not have dirt, and there is no reason to issue a decree in uncommon cases.

Come and hear a different objection to the opinion of the amora from our mishna: The Sages prohibited the people of the city of Tiberias, who ran a cold-water pipe through a canal of hot water from the Tiberias hot springs, from using the water. Granted, according to the opinion of the one who said that the prohibition is due to a decree lest one insulate food in hot ashes, that is the reason that this was prohibited, as it is similar to insulating. The cold-water pipe was placed inside the hot water and was surrounded by it. However, according to the opinion of the one who said that the reason is because one displaces dirt, what is there to say to explain the prohibition?

The Gemara answers: Do you think that the story about Tiberias refers to the latter clause of the mishna? No, it refers to the first clause of the mishna, and it should be understood as follows: The Rabbis and Rabbi Yosei disagree with regard to wrapping an egg in cloths. The Rabbis say: One may not wrap it in cloths and Rabbi Yosei permits doing so. And the Rabbis said the following to Rabbi Yosei: Wasn’t the incident involving the people of Tiberias with derivatives of the sun, as the hot springs of Tiberias are not heated by fire, and nevertheless the Sages prohibited them from using the water? Rabbi Yosei said to them: That is not so. That incident involved derivatives of fire, as the hot springs of Tiberias are hot because they pass over the entrance to Gehenna. They are heated by hellfire, which is a bona fide underground fire. That is not the case with derivatives of the sun, which are not heated by fire at all.

On the same topic, Rav Hisda said:

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Shabbat 39a explores rules on soaking or rinsing salted foods in hot water and debates whether food may be warmed using sun-heated objects.