Rabba said: What is the reason for Rav’s statement that one who declares his intention to establish residence beneath a tree has said nothing at all? It is because the place he designated is not precisely defined. Since he did not establish his residence in one particular location, he did not establish it at all.

And some say an alternative version of Rabba’s statement. Rabba said: What is the reason for the statement of Rav? It is Because he maintains: Anything that cannot be accomplished sequentially, due to halakhic or practical considerations, even simultaneously, cannot be accomplished, as one negates the other. In this case, since one cannot establish residence in an area of four cubits on one side of a tree and proceed to establish residence in an area of four cubits on the other side of the tree, neither can he simultaneously establish residence beneath a tree greater than four cubits.

The Gemara asks: What is the practical difference between these two versions of Rabba’s statement? The Gemara answers: There is a practical difference between them with regard to a case where he said: Let residence be acquired for me in four cubits of the eight or more cubits beneath that tree.

According to the one who said that it is because the place he designated is not precisely defined, here too, the place he designated is not precisely defined, as he failed to specify the precise location of the four cubits in which to establish his residence.

And according to the one who said it is because anything that cannot be accomplished sequentially even simultaneously it cannot be accomplished, this is considered as if he established his residence in four cubits, as here he stated that he is designated only four cubits as his place of residence.

The Gemara proceeds to analyze the matter of Rabba’s statement itself. Rabba said: Anything that cannot be accomplished sequentially even simultaneously it cannot be accomplished. Abaye raised an objection to the opinion of Rabba based on the Tosefta: One who increases tithes, i.e., he tithes two-tenths instead of one-tenth, the remainder of his produce is rendered fit for consumption, as he properly tithed it; however, his tithes are ruined, as the additional tenth is neither a tithe nor is it tithed produce. It is not a tithe because tithe status applies only to one tenth, and neither is it tithed produce as it was not tithed. Since it is unclear which of the two-tenths is the actual tithe and which is not, this produce may neither be treated as a tithe nor as tithed produce.

According to Rabba’s opinion, the question arises: Why should the produce be rendered fit for consumption? Let us say and apply his principle: Anything that cannot be accomplished sequentially; even simultaneously it cannot be accomplished. Since one may not designate two tenths sequentially, one tenth followed by a second tenth, likewise, he should be precluded from simultaneously designating two tenths of his produce as a tithe. Accordingly, it should be considered as though he had not designated any tithe at all, and therefore his produce should not be regarded as tithed.

Gemara answers: The case of a tithe is different, as tithe status takes effect partially, i.e., on less than a unit of produce. As if one said: Let half of each grain of wheat be designated as tithed, it is designated. Just as one can designate an entire grain of wheat as a tithe, he can likewise designate half a grain. In this case too, when one tithes two tenths of the produce, the ruling is not that one tenth is actual tithe and the other tenth is untithed produce mixed with the tithe. Instead, half of each grain of the set-aside portion is designated as a tithe, while the other half of each grain is not. Accordingly, the remainder of the produce is tithed, as one tenth of the total has been designated as first tithe. However, the portion designated as the tithe is ruined, because it is impossible to identify which part of each grain is designated.

Another objection was raised against Rabba’s opinion: Yet there is the case of the animal tithe, which does take effect partially, as one cannot consecrate half an animal for his tithe. Three times a year, the owner of a herd of kosher animals would gather all the animals born during the preceding period into an enclosure and let them out one by one. Every tenth animal would be marked with red paint to indicate that it was sacred. Only an entire animal could be consecrated as animal tithe, not a part of an animal.

And Rabba said: If two animals emerged from the enclosure together as the tenth, and he designated them both as the tenth, the tenth and eleventh animals are intermingled with each other. One is sacred with the sanctity of the animal tithe, while the other remains a peace-offering, but there is no way to determine which is which. The question arises: If the principle that anything which cannot be accomplished sequentially; even simultaneously it cannot be accomplished applies, neither animal is consecrated, as one cannot designate both the tenth and the eleventh animals as the animal tithe, one after the other.

The Gemara answers: The animal tithe is different, as two animals can indeed be designated as animal tithe one after the other in the case of an error. Although one cannot designate the tenth and eleventh animals as the animal tithe ab initio, if he did so in error they are both consecrated.

As we learned in a mishna: If one erred and designated the ninth animal as the tenth, and erred again and designated the tenth as the ninth and the eleventh as the tenth, all three animals are consecrated. The first is consecrated because it was designated as the tenth, the second because it actually is the tenth, while the third is also consecrated because it was designated as the tenth. Apparently, more than one animal can be consecrated as the animal tithe, if designated in error. Here too, a modicum of sanctity applies to the two animals that emerged together and were together designated as the tenth.

The Gemara raises another objection to Rabba’s principle. But there is the case of the forty loaves that accompany a thanks-offering, which are not consecrated if they were designated in error, and likewise are not consecrated if two sets of loaves were designated for the same offering one after the other. And yet it is stated that amora’im disagreed with regard to a thanks-offering that was slaughtered accompanied by eighty loaves, twice the required amount. Ḥizkiya said: Forty of the eighty loaves are consecrated, even though their identity cannot be determined; Rabbi Yoḥanan said: Not even forty of the eighty loaves are consecrated. It would appear that these amora’im disagree whether or not sanctity that cannot take effect in sequence can take effect simultaneously.

The Gemara rejects this contention. Wasn’t it stated with regard to this dispute that Rabbi Zeira said: Everyone, both Ḥizkiya and Rabbi Yoḥanan, concedes that in a case where the donor said: Let forty of the eighty loaves be consecrated, that the forty are consecrated; and in a case where he said: Let forty loaves only be consecrated if all eighty are consecrated, everyone agrees that they are not consecrated. This is in accordance with Rabba’s opinion.

When Ḥizkiya and Rabbi Yoḥanan disagree is with regard a case where the donor designated eighty loaves without stipulation how many he wants consecrated. One Sage, Ḥizkiya, maintains: Although he designated eighty loaves, he seeks to consecrate only forty, and when he sets aside eighty loaves, he merely intends to ensure that he will have forty, and he therefore brought the extra loaves on condition that if the first forty loaves are lost or become ritually impure, the second forty will be consecrated in their place. Consequently, the first forty loaves are consecrated.