Passage
And when he was come into the house, his disciples asked him privately, Why could not we cast him out?
And when he was come into the house, his disciples asked him privately, Why could not we cast him out?
Mark 9:26 And the spirit cried, and rent him sore, and came out of him: and he was as one dead; insomuch that many said, He is dead.
Mark 9:27 But Jesus took him by the hand, and lifted him up; and he arose.
Mark 9:28 And when he was come into the house, his disciples asked him privately, Why could not we cast him out?
Mark 9:29 And he said unto them, This kind can come forth by nothing, but by prayer and fasting.
Mark 9:30 And they departed thence, and passed through Galilee; and he would not that any man should know it.
The verse centers on "come", "house", "disciples", "asked", "privately", and "cast". It is saying that the verse draws attention to "come" and "house", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 27's "But Jesus took him by the hand..." into verse 29's "And he said unto them This kind...", so "come" and "house" belong inside that flow. In Mark context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "come" and "house" with trust shaped by these words, not by a vague optimism outside the passage.