What does the Bible say about holy days?

In Scripture, particularly in Nehemiah 8, a holy day is marked by the reading of God's Word. The essence of a holy day is not about a particular date but rather the reverence given to God through His Word. When the people listen to the Scriptures, understanding and aligning themselves with its truth, they honor God, making that moment a genuinely holy occasion. This stands in contrast to the mere observance of days for self-serving reasons, as seen in Zechariah 7, where the people were told their fasting had been for themselves and not for God.