What does the Bible say about fasting and mourning?

In Matthew 9:15, Jesus teaches that there are seasons for both rejoicing and mourning, stating, 'Can the children of the bridegroom mourn as long as the bridegroom is with them?' This indicates that during Christ's earthly ministry, the time was one of celebration with Him present. However, a time would come when He would be taken away, prompting a season of mourning and fasting. This reflects the ongoing cycles of life within the Christian experience, where we experience joy in Christ's presence and yet also recognize the times of grief, loss, and longing for His return. Fasting is often associated with earnest seeking of God during such times, as believers engage in prayerful dependence on God in all seasons.