he said that the verse states: “The first fruits of your grain, your wine, your oil, and the first of the fleece of your sheep, shall you give him” (Deuteronomy 18:4), implying that its remnants are recognizable for an Israelite, as the notion of a first part indicates that there is another portion remaining which is fit to be consumed by the Israelite. This teruma is excluded as there is no recognizable remnant left that may be consumed by the Israelite, because it is leavened bread. Since even after this portion has been separated the remainder of the produce may not be eaten, that which was separated does not become teruma.

Rav Aḥa bar Rav Avya sat before Rav Ḥisda, and he sat and said in the name of Rabbi Yoḥanan: With regard to grapes that became ritually impure, one should tread on them less than an egg-bulk at a time, and the wine that comes from them is kosher even for libations because it is ritually pure. Apparently Rabbi Yoḥanan holds: The liquid is stored inside the grape, as the juice is not considered to be part of the grape itself but rather stored in the grape as though contained in a receptacle. According to Rabbi Yoḥanan’s opinion, when do these liquids become ritually impure? This occurs only when one squeezes them, and prior to this the juice remains pure even if the grape was impure. And when one squeezes them, there is less than the minimum measure of grape flesh that would transfer ritual impurity, as food can impart ritual impurity only if it is at least an egg-bulk in size.

The Gemara challenges this statement: If that is so, then even if he squeezes an egg-bulk of grapes, the juice will still not become impure. Didn’t we learn in a mishna: In the case of one who is ritually impure with impurity imparted by a corpse and who squeezed olives or grapes in the exact amount of an egg-bulk, the liquid is ritually pure. Once the first drop of liquid is squeezed out, less than an egg-bulk of food remains, and it cannot render the liquid impure. In that case, why did Rabbi Yoḥanan permit squeezing only less than an egg-bulk? The Gemara answers: There, it was speaking of a case where the ruling was after the fact; however, here, it is discussing the ruling ab initio, and the mishna states that one may press juice only from less than an egg-bulk of grapes due to a rabbinic decree lest one come to perform the act of squeezing on more than an egg-bulk, causing the liquid to become impure.

Rav Ḥisda said to Rav Aḥa bar Rav Avya: Who will listen to you and to Rabbi Yoḥanan your teacher with regard to this issue? As, where did the impurity that was in the grape juice go? The Gemara notes that apparently Rav Ḥisda holds: Liquids are absorbed within the fruit and are therefore considered to be part of the grape itself. And since the flesh of the grape became ritually impure, the liquid became ritually impure as well.

Rav Aḥa said to him: Do you not hold that liquids are stored inside the grape? Didn’t we learn in the mishna: In the case of one who is ritually impure with impurity imparted by a corpse and who squeezed olives or grapes in the exact amount of an egg-bulk, using a flat wooden utensil without touching the liquid itself, the liquid is ritually pure. Granted, if you say that the juice is stored inside the grapes, then it is due to that reason that the liquid is pure. But if you say that the liquid is absorbed within the grapes, why is the juice pure? According to this opinion, once the grape itself becomes impure, the juice, which is attached to it and absorbed in it, becomes impure as well.

Rav Ḥisda said to him: With what are we dealing here? We are dealing with a case where the grapes have not been rendered susceptible to ritual impurity, since they have not come in contact with liquids. When do they become susceptible to ritual impurity? This is only once one presses them and they become wet with their own juice. However, when he presses them, they decrease in volume and are lacking the measure of volume required to become impure. This must be the explanation, for if you do not say so, it is difficult to reconcile this mishna with that which was taught in the baraita cited above: To what may this case of teruma of leavened bread be compared? It may be compared to teruma of berries, olives, and grapes that became impure, which can neither be eaten nor burned. However, according to Rabbi Yoḥanan’s statement they may even be eaten, as if one wishes he may tread less than an egg-bulk at a time.

Rava said: It is possible to reject this proof, as even if this action is permitted in principle, there is a rabbinic decree prohibiting it lest he encounter a stumbling block. If one keeps ritually impure fruit of teruma in order to press it for its juice, it is possible that he will forget its status and accidentally eat it. Abaye said to him: Are we concerned about this type of stumbling block? Wasn’t it taught in a baraita: One may light a fire with bread and oil of teruma that became ritually impure? It can be deduced from this baraita that there is no concern that a person will forget and eat these foods. Rava said to him: Bread is only permitted when one throws it among the wood used for fuel so that it is ruined and no longer considered edible. Teruma oil is permitted only when one puts it into a repulsive vessel so that no one will drink it.

With regard to the matter itself, it was taught: One may light with bread and oil of teruma that became ritually impure. The Sages limited the application of this halakha, as Abaye said in the name of Ḥizkiya and Rava said in the name of the Sages from the school of Rabbi Yitzḥak bar Marta that Rav Huna said: They taught that one may use impure teruma as firewood only with regard to bread; however, with regard to wheat, no, one may not light a fire with it, lest one encounter a stumbling block and eat it, because wheat will not become inedible by being placed among the firewood. And Rabbi Yoḥanan said: Even wheat may be used as fuel. The Gemara asks: And why does he permit this? Let us be concerned lest he encounter a stumbling block. The Gemara answers based on what Rav Ashi said with regard to a different issue: