How do we know fasting is a biblical practice?

Fasting is mentioned multiple times in the Bible as a practice undertaken by those who seek deep communion with God. For instance, David fasted when he was mourning for his child (2 Samuel 12:16) and Hannah fasted in her bitterness of soul (1 Samuel 1:10) seeking a son. These accounts show fasting as a heartfelt response to dire circumstances and a means to earnestly pray for God's intervention. The experiences of these faithful individuals indicate that fasting is a serious devotion that God can honor, emphasizing the genuine condition of the heart rather than the act itself.