קשיא לעולא אמר לך עולא הא נמי כברכת המצות דמיא ברכת המצות מאי טעמא משום דהודאה היא הא נמי הודאה היא
This is difficult for the opinion of Ulla, who began but did not conclude the blessing of havdala with: Blessed. The Gemara answers: Ulla could have said to you: This blessing is also considered like a blessing over mitzvot, and therefore it does not require a separate conclusion. The Gemara clarifies this response: What is the reason that blessings over mitzvot do not require a distinctive conclusion? It is because a blessing over a mitzva is a statement of praise, and as it does not include anything unrelated to the praise, e.g., a request or supplication, it is unnecessary to add a separate concluding blessing. This havdala blessing also is comprised only of praise.
רב חנניא בר שלמיא ותלמידי דרב הוו יתבי בסעודתא וקאי עלייהו רב המנונא סבא אמרו ליה זיל חזי אי מקדיש יומא נפסיק וניקבעיה לשבתא אמר להו לא צריכיתו שבתא קבעה נפשה
The Gemara relates that Rav Ḥananya bar Shelemya and other students of Rav were sitting at a meal on Shabbat eve shortly before nightfall, and Rav Hamnuna the Elder was standing over them to serve them. They said to him: Go and see if the day of Shabbat has become sanctified through nightfall. If so, we will interrupt our meal by removing the tables and establish its continuation as the meal for Shabbat. Rav Hamnuna the Elder said to them: You do not need to do this, as Shabbat establishes itself. Whatever you eat after nightfall is automatically considered a Shabbat meal, even without any specific action that designates it as such.
דאמר רב כשם שהשבת קובעת למעשר כך שבת קובעת לקידוש
Rav Hamnuna the Elder explained his ruling. As Rav said: Just as Shabbat establishes food consumption as a regular, set meal with regard to tithes, so Shabbat establishes the requirement to recite kiddush. Generally, one may eat untithed produce in a casual, incidental manner. On Shabbat, however, the strictures of a regular, set meal apply even to casual eating. Consequently, on Shabbat it is entirely prohibited to eat produce from which the appropriate dues and tithes have not yet been separated. Similarly, Shabbat automatically initiates the requirement to recite kiddush, and it is prohibited to eat until one does so. This halakha indicates that whatever one eats at this stage is considered part of his Shabbat meal, even if he does not remove the table and bring it back.
סבור מינה כי היכי דקבעה לקידוש כך קבעה להבדלה אמר להו רב עמרם הכי אמר רב לקידוש קובעת ולא להבדלה קובעת
They understood from it that just as the start of Shabbat automatically establishes the requirement to recite kiddush, so its conclusion establishes the requirement to recite havdala. This would mean that one must interrupt his meal to recite havdala, and whatever he eats after that would not be considered part of his Shabbat meal. Rav Amram said to them: This is what Rav said: Shabbat establishes an obligation to recite kiddush, but it does not establish an obligation to recite havdala.
והני מילי לענין מיפסק דלא מפסקינן אבל אתחולי לא מתחלינן ומיפסק נמי לא אמרן אלא באכילה אבל בשתיה לא
The Gemara comments: And this applies only with regard to the matter of interrupting a meal that one has begun before the conclusion of Shabbat, that one does not have to interrupt to recite havdala. However, one may not begin a meal after nightfall until after reciting havdala. The Gemara adds: And with regard to interrupting also, we only said that one need not interrupt his eating; but with regard to drinking, which is considered less significant, no, one must interrupt his drinking upon nightfall, even if he began drinking before the conclusion of Shabbat.
ושתיה נמי לא אמרן אלא בחמרא ושיכרא אבל מיא לית לן בה
And with regard to drinking also, we only said it is prohibited to drink after nightfall before havdala with regard to wine and beer, which are significant beverages; but with regard to water, we have no problem with it. One may begin drinking water even after Shabbat has concluded and before he has recited havdala.
ופליגא דרב הונא דרב הונא חזייה לההוא גברא דשתה מיא קודם הבדלה אמר ליה לא מיסתפי מר מאסכרה דתנא משמיה דרבי עקיבא כל הטועם כלום קודם שיבדיל מיתתו באסכרה רבנן דבי רב אשי לא קפדי אמיא
The Gemara points out that this last statement disagrees with the opinion of Rav Huna. As Rav Huna saw a certain man drinking water before he recited havdala at the conclusion of Shabbat. He said to him: Is the Master not afraid of the ailment called askara? As it was taught in the name of Rabbi Akiva that whoever tastes anything before he recites havdala, his death will come through askara. Nevertheless, the Gemara notes that the Sages of the school of Rav Ashi were not particular with regard to water. They refrained only from drinking more significant beverages before havdala.
בעא מיניה רבינא מרב נחמן בר יצחק מי שלא קידש בערב שבת מהו שיקדש והולך כל היום כולו אמר ליה מדאמרי בני רבי חייא מי שלא הבדיל במוצאי שבת מבדיל והולך כל השבת כולו הכא נמי מי שלא קידש בערב שבת מקדש והולך כל היום כולו
Ravina raised a dilemma before Rav Naḥman bar Yitzḥak: With regard to one who did not recite kiddush on Shabbat eve, i.e., on the night of Shabbat, what is the halakha with regard to his ability to recite kiddush at any time over the course of the entire day? May one recite kiddush later, or has he lost his opportunity by failing to recite kiddush at the proper time? Rav Naḥman bar Yitzḥak said to him: From the fact that the sons of Rabbi Ḥiyya say that one who did not recite havdala at the conclusion of Shabbat may recite havdala any time over the course of the entire week, it can be inferred that here too, one who did not recite kiddush on Shabbat eve may recite kiddush at any time over the course of the entire day.
איתיביה לילי שבת ולילי יום טוב יש בהן קדושה על הכוס ויש בהן הזכרה בברכת המזון שבת ויום טוב אין בהם קדושה על הכוס ויש בהן הזכרה בברכת המזון
Ravina raised an objection to the opinion of Rav Naḥman bar Yitzḥak from the Tosefta: On the nights of Shabbat and the nights of a Festival there is a mitzva of kiddush over a cup. And there is a requirement to mention the sanctity of the day in Grace after Meals, i.e., the paragraph: May it please [retzei], on Shabbat and: May there rise and come [ya’aleh veyavo], on Festivals. On the day of Shabbat and Festivals, there is no mitzva of kiddush over a cup, but there is a requirement to mention the sanctity of the day in Grace after Meals.
ואי סלקא דעתך מי שלא קידש בערב שבת מקדש והולך כל היום כולו שבת ויום טוב נמי משכחת להו דיש בהן קדושה על הכוס דאי לא קידש מאורתא מקדש למחר אמר ליה דאי לא קתני
Ravina explains his objection: And if it could enter your mind to say that one who did not recite kiddush on Shabbat eve may recite kiddush any time over the course of the entire day, on Shabbat and a Festival too, it can be found that there is a mitzva of kiddush over a cup, for if one did not recite kiddush at night he may recite kiddush the following day. Rav Naḥman bar Yitzḥak said to him: The tanna does not teach cases of what if. In other words, the tanna does not take into consideration the uncommon circumstance of one who failed to recite kiddush on the night of Shabbat.
איתיביה כבוד יום וכבוד לילה כבוד יום קודם ואם אין לו אלא כוס אחד אומר עליו
Ravina raised an objection to the opinion of Rav Naḥman bar Yitzḥak from another source: If there is a choice between the honor of the day of Shabbat and the honor of the night, the honor of the day takes precedence. And if one has only one cup, he should recite over it