Is There Mandatory Fasting In The Bible?

It's Ramadan! The Muslims are fasting. What does the Bible say about fasting? Here is a quote taken from "What Does the Bible Say About Fasting? | Truth Or Tradition?"

QUOTE
The Day of Atonement was a day for people to "afflict your souls" (Lev. 16:29, 31 KJV), which other versions translate as "deny yourselves" (NIV), or "humble your souls" (NASB). The Hebrew word that the KJV translates "afflict" in Leviticus 16:29 and 31 means to "humble, overpower, subdue, oppress, or weaken," depending on the context. The same Hebrew phrase occurs in the context of a woman making a vow to afflict her soul, which could be any vow she made that involved self-denial (Num. 30:13). Although over time the Day of Atonement became a day of fasting, God never specifically said people were to go without eating. Instead, people were to deny themselves, which different people would do in different ways.
UNQUOTE

Additional information on וְעִנִּיתֶ֖ם in "leviticus - What does it means to "afflict your souls" as in Lev. 16? - Biblical Hermeneutics Stack Exchange" quoted below:

QUOTE
The Hebrew text וְעִנִּיתֶם אֶת נַפְשֹׁתֵיכֶם (alternatively תְּעַנּוּ אֶת נַפְשֹׁתֵיכֶם) literally says "and ye shall afflict your souls," and it appears in two separate sections in Leviticus as well as once in Numbers. This text has always been understood to mean afflict your body through fasting. That being said, there is also a spiritual component to Yom Kippur in additional to the physical fast itself. A fairly substantial amount of data from Tanach supports this assertion. A good example is Isaiah 58:3 which reads:
לָמָּה צַּמְנוּ וְלֹא רָאִיתָ עִנִּינוּ נַפְשֵׁנוּ וְלֹא תֵדָע הֵן בְּיוֹם צֹמְכֶם תִּמְצְאוּ חֵפֶץ וְכָל עַצְּבֵיכֶם תִּנְגֹּשׂוּ:
Why have we fasted but You (G-d) have not seen; we have afflicted our souls but You do not know? Behold, on the day of your fast you pursue business, and [from] all your debtors you exact [payment].
In this example, the verb צמנ (fast) is clearly being equated with ענה (afflict).
Furthermore, the Hebrew word נֶפֶשׁ, in addition to meaning "soul," also has a physical meaning related to the human body. Psalms 107:9 is a good example of this:
כִּי הִשְׂבִּיעַ נֶפֶשׁ שׁוֹקֵקָה וְנֶפֶשׁ רְעֵבָה מִלֵּא טוֹב:
For He (G-d) has sated a longing soul, and filled a hungry soul with good.
Above we can see that the dual spiritual/physical meanings of נֶפֶשׁ are being used in the very same verse. So afflicting your soul on Yom Kippur means physically fasting, and being spiritually affected by that fast as well.
Here is an excellent article which discusses this topic in more detail.
UNQUOTE

וְעִנִּיתֶ֖ם
"The tenth day of this seventh month is the Day of Atonement. Hold a sacred assembly and deny (וְעִנִּיתֶ֖ם) yourselves, and present a food offering to the LORD. (Leviticus 23:27 NIV)
"This is to be a permanent statute for you: In the seventh month, on the tenth day of the month you are to practice self-denial (וְעִנִּיתֶ֖ם) and do no work, both the native and the alien who resides among you. (Leviticus 16:29 CSB)
It shall be to you a Sabbath of solemn rest, and you shall afflict (וְעִנִּיתֶ֖ם) yourselves. On the ninth day of the month beginning at evening, from evening to evening shall you keep your Sabbath." (Leviticus 23:32 ESV)