There is a Misva to eat on Ereb Yom Kippur. This Misva is so important that, as the Talmud teaches, a person who eats on Ereb Yom Kippur is considered to have fasted both on that day and on Yom Kippur itself.
What is the concept underlying this obligation? Why are we required to eat on Ereb Yom Kippur?
The Rosh (Rabbenu Asher Ben Yehiel, Germany-Spain, 1250-1327) suggested an analogy to a father who knows that his son would be unable to eat on a given day, and therefore ensures to feed him large amounts of filling foods the day before so he will not suffer as a result of the fast. Similarly, the Rosh said, God "feeds" us on the day before Yom Kippur by commanding us to eat heartily, so that our health and well-being will not be affected by the fast.
The Shoboleh Ha’leket (Rav Sidkiya Ben Abraham, Italy, 1230-1300) suggests the precise opposite reason, namely, that eating heartily the day before a fast makes the fast more difficult. If the body receives large amounts of food one day, it expects the same the next day, and thus fasting becomes a more demanding undertaking. The Torah commanded us to "afflict our souls" ("Ve’initem Et Nafshotechem") on Yom Kippur, and we therefore eat heartily the previous day to make the fasting more uncomfortable.
(One might question, according to this reason, why we do not find a similar Halacha regarding the fast of Tisha B’Ab. Not only is there no Misva to eat heartily on Ereb Tisha B’Ab, but to the contrary, Halacha requires that the final meal before the fast consist of only bread and one cooked food. Apparently, there is a distinction between the fast of Tisha B’Ab, which we observe as an expression of mourning, and Yom Kippur, when we fast as part of the process of repentance.)
The Sefat Emet (Rav Yehuda Aryeh Leib Alter of Ger, Poland, 1847-1905) suggests an entirely different reason for the Misva to eat on Ereb Yom Kippur. One of the obligations that apply on Ereb Yom Kippur is reconciliation with those whom we have wronged. We are obligated before Yom Kippur to ask forgiveness and seek reconciliation as part of our preparations for the day of atonement. The Sefat Emet noted that when people are hungry, they are more agitated and less likely to accept or seek reconciliation. Halacha requires eating heartily on this day so we are all in a pleasant, relaxed mood, which can facilitate peacemaking and reconciliation.
There is a custom to eat double one’s normal food intake on Ereb Yom Kippur. Therefore, if possible, one should estimate his normal daily intake and eat twice that quantity on Ereb Yom Kippur.
The Misva to eat on Ereb Yom Kippur is deemed more important than the Misva of Torah learning. Thus, one should take time away from his Torah study in order to eat a proper meal on Ereb Yom Kippur. The Gemara in Masechet Berachot (8) tells of a certain Rabbi who decided he would spend Ereb Yom Kippur reading "Shenayim Mikra Ve’ehad Targum" (the double reading of the Parsha with the Aramaic translation) for the entire Torah. His colleagues, however, reprimanded him, noting that he has an obligation to eat on that day. The Rabbi did not respond to their criticism, indicating that he accepted their position. This incident demonstrates that this Misva overrides the great Misva of Torah study – a status which is given to very few Misvot.
Hacham Ovadia Yosef rules that the obligation to eat on Ereb Yom Kippur applies to women, just as men, because the reasons given for this obligation – either preparation for the fast or to facilitate reconciliation – apply equally to both men and women.
The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909) records a custom to eat fish at breakfast on Ereb Yom Kippur. The basis for this custom is a story told in a Midrash (cited in the Tur) of a king who instructed his servant to go to the market and buy him a piece of fish. The servant went to the market and found that there was only one piece of fish remaining. He offered the vender a coin for the fish, but a Jew, who also wanted the fish, offered two coins. Intense bidding ensued, and ultimately the Jew outbid the king’s servant and purchased the fish for an exorbitant sum. The servant returned to the king and explained what had happened, and the king immediately summoned the Jew and demanded an explanation for his persistence in bidding on the fish. The Jew explained that it was Ereb Yom Kippur, and he wanted to eat fish in fulfillment of the Misva to eat festively on that day. We therefore eat fish on Ereb Yom Kippur in commemoration of this Jew’s remarkable devotion to this Misva.
The fish is to be eaten only in the morning hours, because foods that raise the chances of Keri (nocturnal emissions) must be avoided in the afternoon of Ereb Yom Kippur, so that one does not become Tameh (ritually impure) on the night of Yom Kippur. This includes fish, dates, eggs, warm milk and fatty meats. These foods should not be eaten during the afternoon of Ereb Yom Kippur.
Summary: There is an obligation for both men and women to eat festively on Ereb Yom Kippur, and one should even take time away from his Torah studies to fulfill this Misva. One should not eat fish, dates, eggs, warm milk or fatty meats in the afternoon of Ereb Yom Kippur. There is a custom to eat fish on the morning of Ereb Yom Kippur.
