It is a Mitzvah to have a sumptuous meal on Purim, including meat and wine.

This meal is held during the day. If one holds it at night, he fails to fulfill his obligation. Nevertheless, after the reading of the Megillah on the night of the 14th (in 'unwalled cities'), or on the night of the 15th after the Megillah Reading (in 'walled cities'), one's meal should be somewhat more festive than usual. One should wear festival clothing and rejoice.

The main Purim meal is held Purim afternoon and is preceded by Minchah. The meal is extended into the night. Most of the meal should, however, be during the day.

When Purim falls on Erev Shabbat, the meal is held early, and is concluded sufficiently before Shabbat for one to be able to partake of the Shabbat meal with a good appetite. Some follow the practice of extending their meal till Shabbat arrives. They then place a Shabbat tablecloth on the table, recite Kiddush, and continue their meal.

The Custom to drink during the Festive meal

The miracle of Purim occurred through wine. Vashti was removed from her throne because of a wine-feast and Esther replaced her. The downfall of Haman was brought about through the wine feasting which Esther held. And through the repentance of the Jews, they expiated their sin in having drunk wine at the feast of Achashverosh

Our Sages of blessed memory, therefore, prescribed the drinking of wine on Purim till intoxication, and they said: 'A person is obligated to drink on Purim till he no longer knows the difference between 'Cursed-is-Haman,' and 'Blessed-is-Mordechai.' In the case, however, of one whose health may be harmed by excessive drinking of wine; or who fears that he might come to levity thereby; or that he might forget the required brachot or prayer - drinking till intoxication is not required. It is sufficient for such a person to drink a little more than is his usual habit, and to take a nap. He thereby fulfills the precept of the Sages: For one who sleeps does not know the difference between a curse and blessing. 

The reason for holding the Purim feast towards evening rather than in the morning, as is the case with other 'Seudot Mitzvah', obligatory feasts, Shabbat or Yom Tov, on Shabbat or Yom Tov is that people are busy sending gifts to their friends during the morning hours.

The Gaon of Vilna gave an explanation which is alluded to in the Megillah: The Purim feast is held in memory of the feast held by Esther for Achashverosh and Haman. She held her feast the third day of the fast, two hours before the advent of night. All Israel fasted the full three days and three nights. Esther alone did not fast the entire third day because of the feast. And this matter is alluded to in Esther's words to Mordechai: 'And I and my maidens will also fast thus.' The Hebrew equivalent for 'thus' is 'ken,' and the numerical value of the two letters which comprise the word 'ken,' is seventy. That is to say - 'I will fast only seventy hours, whereas all Israel are to fast seventy-two hours.'

The Significance of the Purim Feast

The Purim Feast is especially significant in that it elevates the soul as it provides pleasure to the body. It is thus stated in the Zohar that on Purim one may accomplish through bodily pleasure, what he can accomplish on Yom Kippur through bodily affliction.

The people of Israel are invested with bodily holiness as well as with spiritual holiness. And it is proper for their physical actions to be sanctified always, and to be done for the sake of G-d alone. As long, however, as AmaIek exists, he corrupts the purity of Israel's actions. When Amalek's power is weakened and he is subjugated, the physical actions of Israel are again purified.