it does not interpose in the immersion and one does not violate the prohibition against having leaven in his possession during Passover. In a case where the dough does not serve to reinforce the bowl, it interposes in the immersion and one violates the prohibition against owning leaven on Passover. In what case is this statement said? It is in a case where the dough is less than an olive-bulk. However, if it is an olive-bulk, even in a case where it serves to reinforce the bowl it interposes in the immersion and one violates a prohibition by having it in his possession during the Festival.

The Gemara asks: In any case, these baraitot contradict each other. Rav Huna said: Delete the first, lenient baraita from before the stringent one.

Rav Yosef said: Have you removed the tanna’im from the world? It is a dispute between tanna’im. The baraita is in accordance with the ruling of another Sage and is not the result of a flawed baraita, as it was taught in a baraita: With regard to bread that grew moldy and is no longer edible, one is obligated to remove it, due to the fact that it is suitable to be ground and to leaven other dough. Apparently, one is obligated to remove even inedible leaven.

Rabbi Shimon ben Elazar says: In what case is this statement said? In a case where the bread was maintained for consumption; however, a mass of hardened leaven that one designated for the purpose of sitting upon it, not for consumption, is nullified. Rav Yosef infers from the baraita: From the fact that Rabbi Shimon ben Elazar said that this leaven is nullified, this proves by inference that the first tanna maintains that in that case, the leaven is not nullified. Apparently, the first tanna maintains that with regard to any olive-bulk of leaven, even though one renders it null and void, it is not nullified. The respective opinions of these two Sages are presented in the two conflicting baraitot with regard to dough in a bowl.

Abaye said to him: You resolved the contradiction between the baraitot with regard to an olive-bulk of leaven by establishing it as a tannaitic dispute. According to the first tanna, an olive-bulk of leaven cannot be nullified at all, whereas Rabbi Shimon ben Elazar maintains that it can be nullified. However, did you resolve the contradiction with regard to less than an olive-bulk of leaven? Rather, both this baraita and that baraita are in accordance with the opinion of Rabbi Shimon ben Elazar, and nevertheless it is not difficult. This baraita, where he prohibits the dough in a crack of the bowl, refers to a situation where the dough is in the place in the bowl where kneading takes place, as any dough he later inserts into the bowl will come into contact with the dough in the crack. However, in that case, Rabbi Shimon ben Elazar rules leniently, as the dough is not in the place in the bowl where kneading takes place.

Rav Ashi said: Do not say that dough not in the place in the bowl where kneading takes place, refers only to the area on the back of, i.e., outside the basin; rather, it also refers to the area on the edge of the basin, as dough does not come into contact with that part of the bowl.

The Gemara asks: This is obvious; why was it necessary to make that statement? The Gemara answers: Rav Ashi’s statement is necessary lest you say that dough sometimes drips there and it should therefore be considered the place in the bowl where kneading takes place. Therefore, the baraita teaches us that this is not the case, and one is not obligated to remove leavened dough from that part of the bowl.

Rav Naḥman said that Rav said: The halakha is in accordance with the opinion of Rabbi Shimon ben Elazar that a mass of leaven designated for the purpose of sitting upon is nullified.

The Gemara asks: Is that so? Didn’t Rav Yitzḥak bar Ashi say that Rav said: If one covered the surface of a mass of leaven with mortar, the leaven is nullified? The Gemara infers: If he covered it with mortar, yes, it is nullified; however, if he did not cover it with mortar, no, it is not nullified. In this statement, Rav states that a mass of leaven is nullified only if it is covered with mortar.

The Gemara answers: He who teaches this statement does not teach that statement, as there is a dispute between amora’im with regard to Rav’s opinion.

Some say an alternative version of the above statement. Rav Naḥman said that Rav said: The halakha is not in accordance with the opinion of Rabbi Shimon ben Elazar, as Rav Yitzḥak bar Ashi said that Rav said: If one covered the surface of a mass of leaven with mortar, it is nullified. This ruling indicates that if one did not cover the surface with mortar, the leavened dough is not nullified, in accordance with the opinion of the first tanna.

Rav Naḥman said that Shmuel said: With regard to two half-olive-bulk portions of leavened dough with a string of dough connecting between them, one observes: In any case that were the string taken and the portions are taken with it, one is obligated to remove the dough, as the string unites them into an olive-bulk of leaven. And if the portions are not taken with it, one is not obligated to remove them.

Ulla said: We stated this leniency that it is not necessary to remove half-olive-bulk portions of leavened dough only when the segments are in a kneading bowl, stuck separately to the sides of the bowl. However, if they are located in a house, one is obligated to remove them even in the absence of a string of dough connecting the two pieces.

What is the reason for this? It is because a person will sometimes gather them when cleaning his house and they will fall adjacent to each other. If this occurs, the two portions will form an olive-bulk of leavened dough.

Ulla said: The Sages raise a dilemma in the West, Eretz Yisrael: If one piece of leavened bread was in the main area of a house and the other piece was in the upper story, what is the halakha? If one piece is in the house and the other is in a portico, what is the halakha? Similarly, if the two segments are in two houses, one inside the other, what is the halakha?

The Gemara states: Let these dilemmas stand unresolved.

The Sages taught: With regard to bread that grew moldy and was rendered inedible for consumption by a person, but a dog can eat it, it can become impure with the ritual impurity of foods in the measure of an egg-bulk in size, as it is still considered food. If the moldy bread was ritually pure teruma, it may be burned with ritually impure teruma on Passover. Once the bread is no longer fit for human consumption, the prohibition against actively rendering it impure no longer applies. They said in the name of Rabbi Natan: It cannot become ritually impure.

The Gemara asks: In accordance with whose opinion is that which we learned in a mishna: The Sages stated a principle with regard to ritual purity: Any food that is designated as food for a person that becomes impure remains ritually impure until it is rendered unfit to be consumed by a dog. The Gemara reiterates: In accordance with whose opinion is that statement? The Gemara answers: It is not in accordance with the opinion of Rabbi Natan, as his statement indicates that food designated as food for a person is rendered ritually pure as soon as it becomes unfit to be eaten by a person.

The Sages taught: With regard to tanners’ bowls into which one placed flour in the production process of leather, if the flour was placed within three days of the start of Passover, one is obligated to remove it, as it is still considered edible leaven. However, if one added the flour prior to three days before Passover, one is not obligated to remove the contents of the bowl, as the flour will have already been rendered inedible by the odor of the vessel before the beginning of Passover, and is no longer considered edible. Rabbi Natan said: In what case is this statement said? In a case where one did not place animal hides into the bowl; however, if one placed hides into the bowl, even if Passover is within three days of when he placed the flour in the bowl, he is not obligated to remove the flour. Once the foul-smelling hides are placed in the bowl, the flour is certainly no longer edible.

Rava said: The halakha is in accordance with the opinion of Rabbi Natan with regard to this issue. Consequently, there is no set time at which the flour is considered spoiled, as it is considered inedible even one day or even one hour after hides were added to the bowl.

We learned in the mishna: And similarly, with regard to the halakhot of immersion to purify the bowl from ritual impurity, if one is particular about the dough that is stuck in the cracks and he plans to remove it and use it, it is a foreign substance that interposes between the kneading bowl and the water of the ritual bath, and invalidates the immersion of the bowl, leaving it ritually impure. And if he wants the dough to remain in place, its status is like that of the kneading bowl itself and is not an interposition.

The Gemara asks: Is it comparable? How can the mishna compare the halakhot of leaven on Passover to the halakhot of interpositions that invalidate an immersion to purify from ritual impurity? There, with regard to leaven, the matter is contingent upon the measure of the dough, as an olive-bulk of leaven is prohibited. Here, with regard to interpositions that invalidate an immersion, the matter is contingent upon whether or not one is particular about the presence of the dough. In other words, with regard to interpositions it is the attitude of the owner of the bowl that is the decisive factor, not the quantity of the dough.

The Gemara answers that Rav Yehuda said: Say that the mishna should be read: And with regard to interpositions that invalidate an immersion to purify from ritual impurity, it is not so, as it is not the quantity of the dough but the particularity of the owner that is the decisive factor.

Abaye said to him: Doesn’t the mishna teach: And similarly with regard to ritual impurity. The text of the mishna cannot be so drastically emended merely to resolve a difficulty. Rather, Abaye said: This is what the mishna is saying: And similarly