Pope Shenouda III
During the Apostles' fast, the Holy Spirit spoke to them.
Thus the Bible says: “As they ministered to the Lord and fasted, the Holy Spirit said, “Now separate to Me Barnabas and Saul for the work to which I have called them.” Then, having fasted and prayed, and laid hands on them, they sent them away.” (Acts 13:2,3).
How beautiful then is the Lord’s saying to the Apostles about fasting and its relation to casting of devils:
"However, this kind does not go out except by prayer and fasting." (Matt 17:21). Such is the power of fasting, in terrorising devils.
Fasting was not only confined to individuals, but also for whole nations.