One may slaughter animals from pens containing pools of drinking water on a Festival, but not from those found caught in nets or in traps, as they may have been caught on the Festival itself. Rabbi Shimon ben Elazar says: If he came and found the nets and traps out of order on the eve of the Festival, which indicates that an animal had been caught in them, then it is known that the animals were caught on the eve of the Festival, and they are therefore permitted. However, if he checked the nets and traps shortly before the onset of the Festival and found them intact, and he later came and found them out of order on the Festival, it is known that the animals were caught on the Festival, and they are therefore prohibited.

The Gemara poses a question: The baraita itself is difficult because it contains an internal contradiction between its clauses: You first said that if he came and found them out of order on the eve of the Festival, it is known that they were caught on the eve of the Festival. The reason is that he came and found them out of order, but if there is uncertainty, the animals are prohibited. But say now the latter clause of that same baraita: If he came and found them out of order on the Festival, it is known that they were caught on the Festival. The reason is that he came and found them out of order, but in a case of uncertainty, the assumption is that they were caught on the eve of the Festival and are permitted.

The Gemara explains: This is what the baraita is saying: If he came and found them out of order on the eve of the Festival, it is known that they were caught on the eve of the Festival, and they are permitted. But in a case of uncertainty, it is considered as if they were caught on the Festival, and they are prohibited.

Rav Yehuda said that Shmuel said: The halakha is in accordance with the opinion of Rabbi Shimon ben Elazar. All these versions of Shmuel’s ruling are basically in agreement: In a case of uncertainty as to whether or not an item was prepared before the Festival, it is prohibited.

§ It was stated in the mishna that Rabban Gamliel said that the fish brought to him on the Festival by the gentile are permitted. The Gemara asks: Permitted for what purpose? Rav said: They are permitted to be received and moved, but they may not be eaten. Levi said: They are even permitted to be eaten.

Rav said: A person should never prevent himself from attending the study hall for even one moment, and the proof is from this issue; as Levi and I were before Rabbi Yehuda HaNasi when he stated this halakha. In the evening he said: They are permitted to be eaten, but the following morning he said: They are permitted only to be received. I, who was in the study hall in the morning as well, retracted what I said, and taught the matter in accordance with Rabbi Yehuda HaNasi’s second opinion. Levi, who was not in the study hall in the morning, did not retract his statement.

The Gemara raises an objection from the following baraita: If a gentile brought a gift [doron] to a Jew on a Festival, even moist [mefulamin] fish or produce from that same day, they are permitted. Granted, according to the one who said they are permitted to be received, it is well; the halakha is understandable. However, according to the one who said they are permitted to be eaten, is produce from that same day permitted to be eaten? If it was picked from the tree on that day, it is subject to the prohibition of muktze.

The Gemara responds with a counter-question: And according to your reasoning, is produce picked on that same day permitted to be moved? Why, then, is it obvious to you that the produce is permitted to be received? Rather, it must be explained that we are dealing with fish whose gills are still red and with produce that is preserved in greens, not with produce that was actually picked on that day. Why, then, is it called produce of that same day? Because it is fresh and similar to produce picked on that same day. Such produce is permitted not only to be moved, but even to be eaten.

Rav Pappa said that the halakha in this regard is as follows: In the case of a gentile who brought a gift to a Jew on a Festival, if there is of that species still attached to a tree or the ground, it is prohibited to be eaten, as it may be assumed that the gentile picked it that same day. And in the evening as well, after the conclusion of the Festival, it is prohibited for the period of time needed for its preparation, i.e., the period of time necessary to detach it from the tree or the ground, as one may not derive benefit from a prohibited labor that was performed on a Festival on behalf of a Jew.

And if none of that species is still attached to the ground, then if the gift was brought from within the limit, i.e., the distance one may travel on a Festival, it is permitted, as no prohibited labor has been performed.