The disciples were unable to drive out the demon possessing the boy. This must have been a shock to them seeing how they had previously driven out demons when Jesus commissioned them two by two (see Mark 6:12-13).
When the disciples asked why they weren’t able to drive it out, he replied “This kind comes out only by prayer.” or, “prayer and fasting” as other translations put it.
but notice that when Jesus found out about the boy, he didn’t go on a stint of prayer and fasting for days on end. Instead, he simply cast the demon out. Why, then, did he tell his disciples that it comes out by prayer?
It seems that prayer precedes power. Jesus didn’t need to go off on a prayer vigil; he was already a praying man who prayed in such a way that his disciples appealed, “Teach us how to pray.” (Luke 11:1).
Jesus was in constant communion with God. It seems that communion with God is the key to power over the enemy in our own lives as well as the lives of others.
Abba, teach us how to live lives of prayer and not just moments of desperate pleading before the throne. Teach us how to live and love prayer.