That is the reason that it is necessary for the Torah to write: It shall not be found, to indicate that there is a halakha unique to leaven. In this case, it is considered as though it were in his possession. However, according to the one who said: The legal status of an object that effects monetary loss is like that of money, why do I need the phrase: It shall not be found? Obviously, the leaven is prohibited, as it is considered his property. The Gemara answers: It is nonetheless necessary, as it could enter your mind to say: Since when the leaven is intact it returns to the gentile in its pure, unadulterated form, it retroactively did not stand in the Jew’s possession and the Jew did not violate the prohibition against having leaven found on his property. Therefore, the verse teaches us that it is considered as though the leaven belonged to the Jew.

They raised a dilemma before Rava: Is the owner of an animal born into a herd from which the royal tax [arnona] is collected obligated in the mitzva to give the firstborn animal to a priest, as the animal still belongs to a Jew? Or perhaps he is not obligated to give the firstborn animal to the priest, as the obligation does not take effect on an animal partly owned by a gentile. The Gemara elaborates on the parameters of raising the dilemma: In any case where the Jew could dismiss the gentile tax collector with money in lieu of the animals, we do not raise the dilemma, as he is clearly obligated in the mitzva of the firstborn. The authorities own no part of the animal; the Jew merely owes them a monetary debt. Therefore, the animal is the property of the Jew exclusively.

The situation when we do raise the dilemma is specifically where the Jew cannot dismiss the gentile tax collector with money. What is the halakha is this case? He said to them: The owner is exempt from the mitzva of the firstborn. The Sages raised a difficulty: But wasn’t it taught in a baraita that he is obligated in the mitzva of the firstborn? He replied: There it is speaking of a case where the Jew could dismiss the gentile tax collector with money.

Some say that Rava said: The owner of an animal born into a herd from which the royal tax is collected is exempt from the mitzva of a firstborn, even though the Jew could dismiss the gentile tax collector with money. However, the owner of dough from which the royal tax is collected is obligated in ḥalla, despite the fact that the owner of dough partially owned by a gentile is generally not obligated. This is the halakha even though the Jew cannot dismiss the gentile tax collector by paying him the value of the dough.

The Gemara explains: What is the reason for the difference between the halakha of a firstborn animal and the halakha of ḥalla? An animal generates publicity; as everyone knows that this Jew’s animal was confiscated by the authorities, no one will suspect him of intentionally refraining from fulfilling the mitzva. In contrast, dough does not generate publicity. Since not everyone knows that the dough is partially owned by a gentile, those who see a Jew failing to separate ḥalla will suspect him of neglecting the mitzva.

The Sages taught in a baraita: With regard to a gentile who enters the courtyard of a Jew with his dough in his hand, the Jew need not remove the leaven by evicting the gentile from his property. However, if the gentile deposited the leaven with him, and the Jew accepted responsibility, he must remove it. If he designated a room in his house for the gentile to place his leavened food, he need not remove it, as it is stated: ''It shall not be found'' (Exodus 12:19).

The Gemara asks: What is the tanna of the baraita saying? How does the verse: It shall not be found, prove this halakha? Rav Pappa said: The verse cited is referring to the first clause of the baraita, and this is what the tanna is saying: If the gentile deposited the leavened dough with the Jew, he, i.e., the Jew, must remove the dough from his property, as it is stated: It shall not be found.

Rav Ashi said: Actually, the verse cited is referring to the last clause of the baraita, and this is what the tanna is saying: If he designated a room in his house for the gentile to place the leavened dough, he need not remove it, as it is stated: It shall not be found in your houses, and that house is not his; since when the gentile brings the dough into the house, he brings it into his own house, as the space was designated for his use.

The Gemara asks: Is that to say that rental denotes that the renter acquires the rented space as he would a full-fledged acquisition with regard to responsibility for that space? But didn’t we learn in a mishna: Even in a place with regard to which they said it is permitted for a Jew to rent houses to gentiles, e.g., in Syria, they did not say that one may rent it for use as a residence, because the gentiles will bring idolatry into it. And if it enters your mind to say that rental denotes that the renter acquires the rented space as he would a full-fledged acquisition, when the gentile brings the idols into the house he brings them into his own house. Why, then, is it prohibited for the owner to rent it to a gentile?

The Gemara answers: It is different here with regard to leaven, as the Merciful One expresses it using the language: It shall not be found, meaning, that which is found in your possession is prohibited, excluding this leaven, which is not found in your possession. However, with regard to other prohibitions, one who rents a place to others remains somewhat responsible for his property, despite the fact that he does not live there.

Rav Yehuda said that Rav said: One who finds leavened bread in his house on the Festival, i.e., the first day of Passover, covers it with a vessel and burns it at the conclusion of the Festival day. Rava said: If that leaven is consecrated, he need not cover it. What is the reason for this difference? The reason is that people distance themselves from consecrated food in any case, due to the severity of the prohibition against misuse of consecrated property. Therefore, there is no concern that he will eat it.

And Rav Yehuda said that Rav said: If leavened bread belonging to a gentile is in a Jew’s house, he, i.e., the Jew, should erect a barrier ten handbreadths high around it on the fourteenth of Nisan, as a conspicuous marker, so that he will not mistakenly eat it. And if the leaven is consecrated, he need not do so. What is the reason for this halakha? Since people distance themselves from consecrated food, they will not mistakenly eat it.

And Rav Yehuda said that Rav said: With regard to one who sets sail, or one who departs in a caravan traveling to a distant place; if he did so before it was thirty days prior to Passover, he need not remove the leaven from his possession. If he departs within thirty days of the Festival, he must remove the leaven. Abaye said: That which you said, that within thirty days one must remove the leaven, we only said this in a case where his intention is to return home adjacent to Passover (Ran). However, in a case where it is not his intention to return before Passover, he need not remove the leaven.

Rava said to him: But if he intends to return home shortly before the Festival, even if he was gone from Rosh HaShana, shouldn’t he remove the leaven, as failure to do so will lead to his arriving home and discovering leaven in his house just before the Festival? Rather, Rava said: According to that which you said, i.e., that if he leaves before it was thirty days prior to Passover he need not remove the leaven, we said this halakha only if he does not intend to return before Passover. However, if he intends to return, even if he was gone from Rosh HaShana, he must remove the leaven.

And Rava followed his line of reasoning stated elsewhere, as Rava maintains that one must remove all leaven from his possession within thirty days of Passover, even if he will not be there on the Festival itself. As Rava said: With regard to one who turns his house into a storehouse, and there is leaven beneath the stored grain, if he does so before it was thirty days prior to Passover, he need not remove the leaven. Since the leaven is concealed, it is considered removed after the fact. If it is within thirty days, he must remove the leaven, as it is not considered removed ab initio.

And even if this occurred before it was thirty days prior to Passover, we only said that he is not obligated to remove the leaven if it is not his intention to clear away the stored grain before Passover. However, if his intention is to clear away the grain before Passover, he must remove the leaven even before it was thirty days prior to Passover, as perhaps he will not have time to remove the leaven before the Festival.

The Gemara asks: What is the purpose of this period of thirty days that renders it significant? The Gemara answers: As it was taught in a baraita: One asks about and teaches the halakhot of Passover thirty days before Passover. Rabban Shimon ben Gamliel says: One begins studying those halakhot two weeks before the Festival. The Gemara asks: What is the reason for the opinion of the first tanna, that one begins studying the halakhot of Passover thirty days before the Festival?