From the fact that the end of the verse states: ''And in the night he is as a thief,'' apparently the word or at the beginning of the verse is a reference to day, as the verse contrasts between night and or. The Gemara rejects this contention. There, this is what the verse is saying: If the matter is as clear to you as light, that the thief has come into the house prepared to take a life, he is a murderer; and the owner of the house may save himself by taking the life of the intruder. In that case, one may protect himself from a thief who breaks into his house, even by killing the intruder if necessary. And if the matter is as unclear to you as the night, he should be nothing more than a thief in your eyes and not a murderer; and therefore one may not save himself by taking the life of the thief. This verse is not referring to actual day and night; rather, it uses these terms as metaphors for certainty and uncertainty.

The Gemara raises an objection to the opinion that or means evening: ''Let the stars of the twilight be dark; let it look for or but have none; neither let it see the eyelids of the morning'' (Job 3:9). From the fact that the verse states: ''Let it look for or but have none,'' apparently or is day. The Gemara rejects this contention. Actually, it is possible that or, in this context, means light in general, not specifically day. There, Job is cursing his fortune. He said: Let it be His will that this man, referring to himself, will seek light and not find it.

The Gemara raises an objection: ''And I say, yet the darkness shall envelop me, and the or about me shall be night'' (Psalms 139:11). Apparently, or is day. The Gemara rejects this proof. This is what David is saying there: I said after I sinned that darkness shall envelop me in the World-to-Come, which is like day. Now that I know that I have been forgiven, even this world, which is like darkness, is light for me. That being the case, it cannot be derived from here that the word or describes the day.

The Gemara raises an objection from a mishna. Rabbi Yehuda says: One searches on or of the fourteenth of Nisan, on the fourteenth in the morning, and at the time of the removal of leavened bread. The Gemara infers from Rabbi Yehuda’s teaching: From the fact that Rabbi Yehuda says that one searches on or of the fourteenth and on the fourteenth in the morning, apparently or is the evening. In the order of Rabbi Yehuda’s list, or of the fourteenth precedes the morning of the fourteenth. Therefore, or must be referring to the evening. The Gemara concludes: Indeed, learn from it that this is the case.

The Gemara raises an objection from a different source: From when on the fourteenth of Nisan is it prohibited to perform labor, for those who are accustomed not to work on Passover eve? Rabbi Eliezer ben Ya’akov says: From the time of or. Rabbi Yehuda says: From sunrise.

Rabbi Eliezer ben Ya’akov said to Rabbi Yehuda: And where have we found precedent for a day, in part of which the performance of labor is prohibited, and in another part of which the performance of labor is permitted? If, as you claim, the prohibition against performing labor takes effect only from sunrise, whereas the fourteenth of Nisan begins with the emergence of stars the previous evening, it is permitted to perform labor during the first part of the fourteenth, while during the second part of the same day labor is prohibited. He said to him: The fourteenth day itself can prove to be a precedent, as in part of it, from the beginning until the sixth hour of the day, the eating of leavened bread is permitted, and during another part of it the eating of leavened bread is prohibited.

With regard to the matter under discussion, the Gemara infers: From the fact that Rabbi Yehuda says that it is prohibited to perform labor from sunrise, apparently the word or that Rabbi Eliezer ben Ya’akov is saying, is referring to the evening. This is an additional proof that or means night. The Gemara rejects this contention: No, this is not a proof. What is meant by or? It means dawn. The dispute of the tanna’im is not whether the prohibition of labor begins at night or in the morning. Rather, they disagree as to whether labor is prohibited from dawn or only from sunrise.

The Gemara challenges this assumption: If so, consider that which Rabbi Eliezer ben Ya’akov said to Rabbi Yehuda: Where have we found precedent for a day, in part of which the performance of labor is prohibited, and in another part of which the performance of labor is permitted? Let him say to himself: Isn’t there the night, during which even Rabbi Eliezer ben Ya’akov himself permits performance of labor at night? He certainly would not raise a difficulty against the opinion of Rabbi Yehuda, which is equally difficult according to his own opinion.

The Gemara rejects this contention. This is what Rabbi Eliezer ben Ya’akov is saying: Granted, according to my opinion, I find situations in which the Sages distinguished between the day and the preceding night, as we learned in a mishna with regard to a lenient communal fast: Until when may one eat and drink before the fast? It is permitted to eat and drink until dawn; this is the statement of Rabbi Eliezer ben Ya’akov. Rabbi Shimon says: One may eat until the call of the rooster, which precedes dawn. In that case, the Sages distinguished between day and night. However, according to your opinion, where do we find a halakha with regard to which the Sages divided the day itself?

Rabbi Yehuda said to Rabbi Eliezer ben Ya’akov: The day of the fourteenth itself can prove my opinion, as during part of it, the eating of leavened bread is permitted, and during part of it the eating of leavened bread is prohibited. The Gemara comments: Rabbi Yehuda has spoken well to Rabbi Eliezer; how can Rabbi Eliezer ben Ya’akov counter this contention? The Gemara answers that this is what Rabbi Eliezer is saying to him in response: I said to you the prohibition of labor, which is by rabbinic law, and you said to me the prohibition of leavened bread, which is by Torah law. With regard to a Torah prohibition, it is possible that until this point, God prohibited doing so, and until that point, God permitted doing so, as the halakha is determined by a Torah decree. On the other hand, rabbinic prohibitions are enacted within clearly defined categories; in this case, an entire day.

The Gemara asks: And what is the response of the other Sage, Rabbi Yehuda, to this contention? The Gemara answers: Rabbi Yehuda notes that the hours when the prohibition of leaven is in effect on the morning of the fourteenth are determined by rabbinic law. Despite the fact it is prohibited by Torah law to eat leaven from midday, the distinction within the morning hours between the time when one may consume leaven and the time when one may derive benefit from leaven but not consume it is determined by the Sages. Apparently, the Sages institute ordinances that apply to part of a day.

The Gemara asks: And how can the other Sage, Rabbi Eliezer ben Ya’akov, respond to this claim? The Gemara answers: Rabbi Eliezer ben Ya’akov would say that in this case the Sages established a preventive measure for a Torah law, and decrees of this type are at times in effect for only part of the day. By contrast, when the Sages instituted independent ordinances, they invariably did so for the entire day. In any case, this source does not conclusively prove that or means evening.

The Gemara raises an objection: The court messengers kindle torches on the mountaintops as a signal that the court has sanctified and established a new month only for a month that appeared at its proper time, on the thirtieth day of the previous month, to sanctify it on that day. And when do the messengers kindle these torches? They light them on or of its additional day, at the end of the thirtieth day from the beginning of the previous month, leading into the evening of the thirty-first day. The thirtieth day is called the additional day because it is sometimes appended to the previous month, which would otherwise consist of twenty-nine days. Apparently, or is the evening, as the court messengers would certainly not light the bonfires by day. The Gemara concludes: Indeed, learn from it that this is the case.

The Gemara raises an objection: If a priest was standing all night and sacrificing the limbs of offerings on the altar, in the ora he is required to sanctify his hands and feet again, by washing them in water from the basin; this is the statement of Rabbi Yehuda HaNasi. Since a new day has begun, the priest must wash his hands and feet from the basin, a prerequisite for each day’s service. With regard to the issue under discussion, apparently or means day. The Gemara rejects this contention: This is not a conclusive proof, as ora is different, and indeed it is referring to the day. However, the word or may yet refer to the evening.

Mar Zutra raises an objection