Charles Spurgeon Commentary Mark 9:29

"And he said unto them, This kind can come out by nothing, save by prayer." — Mark 9:29 (ASV)

This kind can come forth by nothing, but by prayer and fasting.

God does not give us everything in answer to one prayer. It may be necessary for some blessings that the prayer should be reiterated—that it should deepen—that it should grow into an aching. It may even be necessary, so that a blessing may come, that fasting should be used with prayer to show the petitioner's intense eagerness and earnestness.

Now notice Mark 9:38.