How do we know the significance of fasting according to the Bible?

The significance of fasting, as discussed in Zechariah 7, lies in its intended purpose—humbling oneself before God and seeking His will. The Israelites had turned fasting into a hollow ritual, seeking to honor their past without recognizing their present need for repentance. True fasting, as outlined in the Scriptures, should reflect a heart that genuinely desires to draw nearer to God and acknowledge personal sin. In contrast, fasting merely for the sake of tradition, as seen in the Israelites' practices, misses the point of sincere worship and relationship with God. Therefore, the authenticity of one's fasting is measured by the inward attitude toward God rather than outward appearances.