וַיֹּ֣אמֶר לָהֶ֡ם לְכוּ֩ אִכְל֨וּ מַשְׁמַנִּ֜ים וּשְׁת֣וּ מַֽמְתַקִּ֗ים וְשִׁלְח֤וּ מָנוֹת֙ לְאֵ֣ין נָכ֣וֹן ל֔וֹ כִּֽי־קָד֥וֹשׁ הַיּ֖וֹם לַאֲדֹנֵ֑ינוּ וְאַל־תֵּ֣עָצֵ֔בוּ כִּֽי־חֶדְוַ֥ת יְהוָ֖ה הִ֥יא מָֽעֻזְּכֶֽם׃
느헤미야가 또 이르기를 너희는 가서 살찐 것을 먹고 단 것을 마시되 예비치 못한 자에게는 너희가 나누어 주라 이 날은 우리 주의 성일이니 근심하지 말라 여호와를 기뻐하는 것이 너희의 힘이니라 하고
Mishneh Torah, Scroll of Esther and Hanukkah
And it is not only the Hallel of Chanukah that is from the words of the Scribes. Rather the reading of the Hallel is always from the words of the Scribes on all of the days in which we complete the Hallel. And it is a commandment to complete the Hallel on eighteen days in the year. And these are them: The eight days of the Festival (Sukkot); eight days of Chanukah; the first day of Passover; and the day of [Shavuot]. But there is no Hallel on Rosh Hashanah and Yom Kippur because they are days of repentance, awe and fear — not days of excessive joy. And they did not ordain Hallel on Purim, because the Scroll [of Esther that is read on it] is the Hallel.
Mishneh Torah, Rest
The seven days of Passover and the eight days of Sukkot along with the other holidays are all forbidden for eulogizing and fasting. And one is obligated to be joyful and of a good heart on them—he, his children, his wife, the members of his household and all who accompany him. As it is stated (Deuteronomy 16:14), "And you shall rejoice in your holiday, etc." Even though the joy that is mentioned here is [referring to] peace offerings—as we explain in the Laws of the Festival Offering—included in that joy is for him, his children and the members of his household to rejoice—everyone according to what is fit for him.