Just as sprinkling the water of purification is prohibited by rabbinic decree and does not override Shabbat, even for the purpose of a mitzva, so too, telling a gentile to perform a prohibited labor Shabbat is prohibited by rabbinic decree and does not override Shabbat. How, then, could Rabba suggest that they instruct a gentile and thus transgress a rabbinic decree?

Rav Yosef said to him: But do you not differentiate between a rabbinic decree that involves an action and a rabbinic decree that does not involve an action? As the Master, Rabba, did not say to the gentile: Go and heat water on Shabbat, but only told him to transfer something from one domain to another, which does not involve an action and is therefore less severe.

Upon hearing of this incident and the ensuing discussion, Rabba bar Rav Ḥanan said to Abaye: In an alleyway that contains two such great people as the Sages Rabba and Abaye, is it possible that there could be neither an eiruv nor a merging of alleyways? Abaye said to him: What should we do? As for the Master, Rabba, it is not his manner to go and collect for the eiruv from all the residents of the alleyway. As for myself, I am busy with my studies and do not have time to take care of this issue. And they, the other residents of the alleyway, do not attend to such matters.

And if I were to transfer to the residents of the alleyway a share of the bread in my basket, so as to allow them to join a merging of alleyways, since if they would want to take it from me it would be impossible for me to give it to them because I am poor and need the small amount of bread that I can afford for myself, the merging of alleyways would therefore be invalid.

As it was taught in a baraita: If one of the residents of an alleyway requested wine or oil from the merging of alleyways, and they did not give him any, the merging of alleyways is invalid. This is because it has become evident that he is not considered a true partner in it.

Rabba bar Rav Ḥanin further asked: But let the Master transfer to them a quarter-log of vinegar in one of his barrels; certainly even Abaye could afford to provide such a small amount of vinegar for the rest of the residents. Abaye replied: It was taught in a baraita: One may not use food in a storeroom for a merging of alleyways, as it is not clear which specific portion of the food is being set aside for that purpose. The same halakha would apply to an unspecified quarter-log of vinegar in a barrel.

Rabba bar Rav Ḥanin raised a difficulty. Wasn’t it taught in a different baraita: One may use stored food for a merging of alleyways? Rav Oshaya said: This is not difficult. This source, the baraita that states that one may not use stored food for a merging of alleyways, is in accordance with the opinion of Beit Shammai. And that source, the baraita that states that it is permitted to do so, is in accordance with the opinion of Beit Hillel. Beit Shammai and Beit Hillel disagree about whether or not to apply the principle of retroactive clarification.

As we learned in a mishna: If a corpse is in a house, and the house has many entrances, they are all ritually impure. It is currently unknown through which entrance the corpse will be removed from the house, and any of the entrances might be used for this purpose. Therefore, they all contract impurity imparted by a corpse in a tent as though the corpse had already passed through each of them.

However, if only one of them was open, that particular entrance is ritually impure, as the corpse will certainly be removed through it, while all of the others are ritually pure. If one decided from the outset to remove the corpse through one of the entrances, or through a window that is four by four handbreadths in size, it saves all of the other entrances from contracting impurity.

Beit Shammai say: This applies only if he had decided on an entrance before the person died, so that the entrance through which his body would be removed was already determined at the time of death. But Beit Hillel say: This applies even if he decided the matter only after the person had died, as the principle of retroactive selection is invoked and the entrance through which the deceased will be removed has been retroactively established. The same dispute applies to a merging of alleyways with an unspecified portion of stored food, and it revolves around whether it can be retroactively established that a specific portion had been set aside for the merging of alleyways.

The Gemara relates another story about a certain baby whose warm water, which had been prepared for his Shabbat circumcision, spilled. Rava said to those who had brought the matter to his attention: Let us ask the baby’s mother. If the warm water is necessary for her health, let a gentile heat water for the baby indirectly, through his mother. In other words, the water may be heated for the mother, as a woman after childbirth is regarded as being in a life-threatening situation.

Rav Mesharshiya said to Rava: The baby’s mother is healthy enough that she is eating dates. Certainly her condition is not precarious enough to necessitate the heating of water. Rava said to him: It is possible to say that it was merely a ravenous hunger that had seized her, and she is unaware of what she is eating, but in fact she is still dangerously ill.

The Gemara relates yet another similar incident: There was once a certain baby whose warm water, which had been prepared for his Shabbat circumcision, spilled. Rava, who had water in his courtyard but had not established a joint eiruv with the adjacent courtyard where the baby was located, said to those who asked him about the matter: Clear away my belongings from the men’s chamber, which opens directly into my courtyard, to the inner women’s chamber, which does not. Rava was concerned that he would come to carry his belongings into the courtyard, which would be prohibited once he had renounced his rights to it. And I will go and sit there, in the women’s chamber, and I will renounce my rights to this courtyard in favor of the residents of the baby’s courtyard, so that they will be able to transfer the warm water from one courtyard to the other.

Ravina said to Rava: Didn’t Shmuel say: There is no renunciation of rights from one courtyard to another. How, then, can you renounce your rights to your courtyard in this manner? Rava said to him: I hold in accordance with the opinion of Rabbi Yoḥanan, who said: There is renouncing of rights from one courtyard to another.

Ravina then asked Rava: But if the Master does not hold in accordance with the opinion of Shmuel,