Midrash su Ester 9:22

(Ib. b) We are taught: R. Eliezer says: "A man shall do nothing else on a holy day, but either eat and drink or sit and study." R. Joshua says: "A man must divide the holy day, one-half to be spent in eating and drinking, and the other half [in learning] at the house of study." "Both," said R. Jochanan, "make their deductions from the same passages. One passage says (Deu. 16, 8) A solemn assembly to the Lord, thy God, and another passage says (Num. 29, 35) 'Have ye' a solemn assembly. [How can both of these passages be reconciled? If it is to be solemn to 'the Lord,' then why say 'have ye'?] R. Eliezer, therefore, is of the opinion that this intends to suggest a celebration either for God or for yourself;" but R. Joshua is of the opinion that it means to divide the day, one-half for God and one-half for yourself." R. Eliezer said: "All agree that on the Shebouth festival, a certain part should also be devoted for yourself, because it is the day on which the Torah was given [hence we ought to rejoice on that occasion]." Rabba said: "All agree that the Sabbath should also be devoted for yourself. The reason of it is (Is. 58, 13) And thou shalt call the Sabbath rejoicing." R. Joseph said: "All agree that Purim should also be devoted for yourself; explanation is found in (Esther 9, 22) days of feasts and rejoicing." Mar, the son of Rabina, used to fast the whole year round except on Shebuoth (Feast of Weeks), Purim (Feast of Esther) and the day preceding Yom Kippur (Day of Atonement); on Shebuoth, being the day Israel received the Torah; Purim, concerning which it is written (Est. 9, 22) … days of feast and rejoicing; the day preceding Yom Kippur, because R. Chiya b. Rab, of Difthi, recited: (Lev. 23, 32) And ye shall afflict yourselves on the ninth day of the month. Do we fast on the ninth day? Behold it is only on the tenth that we fast! But this means to teach us that whoever eats and drinks on the ninth. Scripture accounts to his credit, as though he had fasted on both the ninth and tenth days.