It is deduced from the fact that it is not taught in their regard that those who eat non-sacred produce according to the level of ritual purity required for sacrificial food must treat the produce with a higher standard with regard to their degree of purity, like those who actually partake of sacrificial food.

The Gemara asks: But perhaps the reason for this fact, that a higher standard is not taught with regard to those who actually partake of sacrificial food, is that these foods are not on a distinct level of ritual purity, as, if they are similar to the level of teruma, teruma has already been taught; and if they are similar to non-sacred produce, non-sacred produce has also already been taught. As we learned in a baraita that they are not considered to be on a level of their own: Non-sacred foods prepared according to the level of ritual purity required for sacrificial food are like non-sacred food; Rabbi Elazar, son of Rabbi Tzadok, says: They are like teruma, but not like sacrificial food. Therefore, the fact that this level is not explicitly mentioned affords no proof.

Rather, the proof is derived from the last clause in the mishna: Yosei ben Yo’ezer was the most pious member of the priesthood, and yet his cloth was considered impure by the treading of a zav for those who ate sacrificial food. Yoḥanan ben Gudgeda would eat non-sacred foods prepared according to the level of ritual purity required for sacrificial food all his days, and nevertheless his cloth was considered rendered impure by the treading of a zav for those preparing the purification waters.

The Gemara infers from this: For the purifying waters, yes, his cloth was considered to have ritual impurity imparted by treading, but for sacrificial food, no, it was not considered to have ritual impurity imparted by treading. Apparently, he maintains that non-sacred produce prepared according to the level of ritual purity required for sacrificial food is like sacrificial food, as one who is particular to preserve the ritual purity required for sacrificial food even with regard to non-sacred produce is considered pure even with regard to sacrificial food themselves.

§ With regard to the particular care that must be taken to prevent any suspicion that one’s clothes have contracted impurity, Rabbi Yonatan ben Elazar said: If the shawl of one who was stringent with regard to ritual purity fell off of him, and he said to another person: Give it to me, and he gave it to him, the shawl is impure. Even if the other individual is himself pure, since his attention was diverted at that moment from being cautious with regard to impurity, it is as though the shawl were rendered impure. Similarly, Rabbi Yonatan ben Amram says: If one’s Shabbat clothes were switched for his weekday clothes and he wore them, they are impure. His assumption that they were different clothes than the clothes he had intended to wear is enough of a distraction to spoil his caution against impurity.

Rabbi Elazar bar Tzadok said: There was an incident involving two women who were wives of ḥaverim, who are meticulous in observance of halakha especially with regard to matters of impurity, whose clothes were switched in the bathhouse; and the incident came before Rabbi Akiva and he declared the clothes impure. This demonstrates that an unintentional act is considered a lapse of attention, which renders the items impure, even if there was no other reason to consider them impure.

Rabbi Oshaya strongly objects to this: However, if that is so, one who inserted his hand into a basket to take a loaf of wheat bread, and a loaf of barley bread came up in his hand instead; in that case, too, will you say that the loaf is rendered impure?

And if you would say, indeed, this is correct, but isn’t it taught in a baraita: One who is minding a barrel to ensure its ritual purity on the assumption that it is a barrel of wine and it is found to be of oil, it is ritually pure in the sense that it does not transmit impurity? This indicates that one’s lack of knowledge with regard to the identity of the item he is minding does not itself cause impurity. The Gemara rejects this: But according to your line of reasoning, say the latter clause of that same baraita: And it is prohibited to be eaten, which indicates that the supervision is insufficient in this case. The Gemara asks: Why is it that the barrel’s status is pure and yet there is a prohibition against eating its contents? If the supervisor’s error does not harm the food’s ritually pure status, one should likewise be permitted to eat it.

Rabbi Yirmeya said: The baraita is referring to one who says: I guarded it from things that render it impure but not from things that invalidate it. In other words, he was careful to guard it only from being rendered impure with a severe degree of impurity, which causes anything it renders impure to render others impure in turn, but not from a lesser degree of impurity that merely invalidates it for use but does not enable it to render other items ritually impure. Since he guarded it from impurity, it is considered pure with regard to rendering other items impure, but it still may not be eaten, in case it was invalidated by an impure object.

The Gemara asks: And is there guarding by half measures; can it be said that one was careful with regard to only a particular type of impurity? The Gemara responds: Yes, as it is indeed taught in a baraita: If one inserted his hand into a basket filled with figs, and the basket was placed on his shoulder, and a shovel was in the basket, and his mind was on the basket to guard it from impurity, but his mind was not on the shovel, the basket is pure and the shovel is impure.

The Gemara asks: Why is the basket pure? Let the shovel render the basket ritually impure, if the former is in fact impure. The Gemara answers: The halakha is that a vessel cannot render a different vessel impure. Therefore, the basket remains pure. The Gemara asks another question: And let it render impure any food that is inside the basket, as food is not a vessel and can therefore be rendered impure by a vessel. Ravina said: The baraita is referring to one who says: I guarded the shovel from things that render it ritually impure, which is why it cannot render other objects impure, but I did not guard it from things that invalidate it, so it is impure. Consequently, there is no proof from here that the contents of the barrel in the earlier case may not be eaten.

Returning to the prior discussion, the Gemara states that in any case it is difficult. Why should an object be impure just because the one guarding it was mistaken with regard to the identity of its contents; how would this accord with the baraita that explicitly taught that if one minds a barrel under the assumption that it is wine and it turns out to contain oil, the oil is pure and cannot render others impure?

And Rabba bar Avuh raised a further objection: There was an incident involving a certain woman who came before Rabbi Yishmael and said to him: Rabbi, I wove this garment in a ritually pure state, but my mind was not on it to guard its state of purity. In other words, although I did not intend to guard it in this manner, I am certain that no impurity came into contact with it. And during the interrogations that Rabbi Yishmael conducted with her, to see if it had remained in a state of purity, she happened to say to him: Rabbi, a menstruating woman pulled the rope with me as I was weaving, and the garment was therefore rendered fully impure by a menstruating woman moving it. Rabbi Yishmael said: How great are the words of the Sages when they said: If one’s mind is focused on guarding it, it is pure; if one’s mind is not focused on guarding it, it is impure. Since she was not focused on preserving the garment’s pure state, it contracted impurity without her noticing.

There was another incident involving a certain woman who came before Rabbi Yishmael and said to him: Rabbi, I wove this cloth in a state of ritual purity, but my mind was not on it to guard it from impurity. And during the interrogations that Rabbi Yishmael conducted with her, she said to him: Rabbi, a thread of mine that was woven into the cloth snapped and I tied it with my mouth. It can be assumed that the thread became moist from her spittle, which means that if that thread was touched by a source of impurity, the cloth would be rendered ritually impure by contact with impure liquids. This is because the Sages decreed that any impurity that touches liquid renders the liquid ritually impure to the first degree, so any vessel that comes into contact with the liquid would be impure to the second degree.

Rabbi Yishmael said: How great are the words of the Sages when they said: If one’s mind is focused on guarding it, it is pure; if one’s mind is not focused on guarding it, it is impure. In any case, if one intends to keep something in a state of ritual purity, a mistake on his part with regard to its identity is not considered enough of a distraction to render the item impure, unlike the baraita that explicitly taught that if one minds a barrel under the assumption that it is wine and it turns out to contain oil, the oil is pure and cannot render others impure.

The Gemara clarifies: Granted, according to Rabbi Elazar bar Tzadok there is no difficulty, as in the case of the two wives of ḥaverim whose garments were switched it can be said that each of them says to herself: My colleague is the wife of an am ha’aretz, and not a ḥaver. And she diverts her mind from her garments, as she is certain that they have already been rendered impure, and a distraction of this kind makes it likely that the garment contracted impurity. It is therefore considered impure.

Likewise, according to Rabbi Yonatan ben Amram there is no difficulty either, as with regard to the case of one who switched his Shabbat clothes with his weekday clothes, it can also be said that since he is more protective of Shabbat clothes, he will divert his mind from that higher level of protection if he thinks that they are weekday garments. A distraction of this kind makes it likely that the garment contracted impurity, so it is considered impure. But according to Rabbi Yonatan ben Elazar, who deals with the case where one’s shawl fell and another person lifts it up, why should this be considered a distraction? Let him guard his garments from ritual impurity while they are in the other person’s hands; why should they be considered impure?

Rabbi Yoḥanan said: It is a presumption that a person does not guard that which is in another’s hand. Since the object is in the hands of another, he will inevitably be distracted from guarding it. The Gemara asks: And can one indeed not guard an item in the hand of another?