[Psalms (“Tehillim”), the first book of the section in the Hebrew Bible called Writings, is an anthology of 150 poems attributed to King David and to others.]
עִבְד֣וּ אֶת־ה' בְּשִׂמְחָ֑ה בֹּ֥אוּ לְ֝פָנָ֗יו בִּרְנָנָֽה׃
Worship the LORD in gladness; come into His presence with shouts of joy.
[Proverbs (“Mishlei”), the second book of the section in the Hebrew Bible called Writings, contains guidance for living a wise, moral, and righteous life, in the form of poems and short statements.]
(יח) עֵץ־חַיִּ֣ים הִ֭יא לַמַּחֲזִיקִ֣ים בָּ֑הּ וְֽתֹמְכֶ֥יהָ מְאֻשָּֽׁר׃ (פ)
[The Mishnah is the first major work of rabbinic literature, consisting of teachings transmitted over hundreds of years and compiled around 200 CE. Pirkei Avot (literally “Chapters of the Fathers,” also known as “Ethics of our Fathers”) consists of short statement of advice, ethics and wisdom.]
בן זומא אומר: ..איזהו עשיר? השמח בחלקו, שנאמר: (תהלים קכח ב): "יגיע כפיך כי תאכל אשריך וטוב לך".אשריך, בעולם הזה .וטוב לך, לעולם הבא.
...Who is the rich one? He who is happy with his lot, as it says, "When you eat [from] the work of your hands, you will be happy, and it will be well with you" (Psalms 128:2). "You will be happy" in this world, and "it will be well with you" in the world to come.
[The Talmud is the textual record of generations of rabbinic debate about law, philosophy, and biblical interpretation, compiled between the 3rd and 8th centuries and structured as commentary on the Mishnah. Tractate Taanit (“Fast”) is part of the Talmud and discusses laws and stories relating to fast days and other public prayers.]
[The Mishneh Torah (“Repetition of the Torah”) is a monumental legal code written by Rabbi Moshe ben Maimon (Rambam, also know as Maimonides) in Egypt in the late 12th century.]
יֵשׁ בִּכְלַל אוֹתָהּ שִׂמְחָה לִשְׂמֹחַ הוּא וּבָנָיו וּבְנֵי בֵּיתוֹ כָּל אֶחָד כָּרָאוּי לוֹ:
כֵּיצַד. הַקְּטַנִּים נוֹתֵן לָהֶם קְלָיוֹת וֶאֱגוֹזִים וּמִגְדָּנוֹת. וְהַנָּשִׁים קוֹנֶה לָהֶן בְּגָדִים וְתַכְשִׁיטִין נָאִים כְּפִי מָמוֹנוֹ. וְהָאֲנָשִׁים אוֹכְלִין בָּשָׂר וְשׁוֹתִין יַיִן שֶׁאֵין שִׂמְחָה אֶלָּא בְּבָשָׂר וְאֵין שִׂמְחָה אֶלָּא בְּיַיִן.
Included in [this charge to] rejoice is that he, his children, and the members of his household should rejoice, each one in a manner appropriate for him.
What is implied? Children should be given roasted seeds, nuts, and sweets. For women, one should buy attractive clothes and jewelry according to one's financial capacity. Men should eat meat and drink wine, for there is no happiness without partaking of meat, nor is there happiness without partaking of wine.
[Likutei Moharan is a collection of Chasidic and mystical teachings by Rabbi Nachman of Breslov, who lived 1772-1810 in Ukraine.]
It is a great mitzvah to always be happy, and to make every effort to determinedly keep depression and gloom at bay.
[Midrash Sekhel Tov (“Good Understanding”) is a 12th century midrash on Genesis, Exodus, and a part of Leviticus, compiled in Italy by Rabbi Menachem ben Shlomo.]