Shemini Atzeres Shiur 5781

2. On Friday, it is forbidden to partake of a celebratory feast that one would not ordinarily partake of on a weekday. [This is so] Even if it is an Erusin meal, because of the honor of Shabbat, so that one will enter Shabbos desiring to eat and partake of the Shabbos meal with an appetite. All day is forbidden. RAMA: A Friday meal where one says zimun, such as a bris milah or pidyon ben it is permitted as seen above, and this is the simple custom. To eat and drink without partaking of the meal, even a meal that one ordinarily partakes of on the weekday, all day is permitted to begin according to the law. Nevertheless, it is a mitzvah to refrain from eating a meal from the ninth hour onward.

1. The Laws of Being Joyful on a Yom Tov, 4 Seifim: It is a holiday mitzvah to spend half the time in the House of Study and half of the time eating and drinking. One should not skimp on holiday expenses; it must be honored and enjoyed like Shabbat. Rem"a: It is forbidden to eat after Mincha on the day before a holiday, just like for Shabbat, and this is part of honoring it (Rambam chapter 6). However, if the day before the holiday is Shabbat, one can have the third meal and eat a bit of bread in honor of the holiday. It is a mitzvah to knead bread on the day before the holiday in honor of the holiday (Mahari"l laws of a holiday) like on Friday, as was explained above in chapter 342. It is an obligation to eat two loaves of bread and to include wine in the meal. Holiday clothes should be nicer than those for Shabbat. It is not the practice to make a third meal. (And on a holiday, we tarry when going to synagogue and quickly leave synagogue because of the holiday joy (Gemara end of chapter "Hakoreh Omed").

However, if you say that we learned in the mishna that one may not eat adjacent to the greater minḥa, what is the greatness of Agrippa? The prohibition against eating had already taken effect at the outset, right after midday. Rather, it must be that we learned in the mishna that it is prohibited to eat adjacent to the lesser minḥa, and Agrippa was praised for changing his regular routine, despite the fact that he was not obligated to do so.