Mark 9:28

And, when he had gone into a house, his disciples, privately, were questioning him - Why, were, we, not able to cast it out?

Mark 7:17

And, when he entered into a house from the multitudes, his disciples began to question him as to the parable;

Matthew 13:10

And the disciples, coming near, said to him, Wherefore, in parables, art thou speaking to them?

Matthew 13:36

Then, dismissing the multitudes, he went into the house, and his disciples came near to him, saying - Make quite plain to us the parable of the darnel of the field.

Matthew 15:15

And Peter, answering, said unto him, Declare to us the parable.

Matthew 17:19-20

Then, the disciples, coming near, to Jesus, privately, said - Wherefore could, we, not cast it out?

Mark 4:10

And when he was alone they who were about him with the twelve questioned him as to the parables;

Mark 4:34

but, without a parable, was he not speaking unto them, - privately, however, unto his own disciples, was he explaining all things.

Treasury of Scripture Knowledge

Summary

And when he was come into the house, his disciples asked him privately, Why could not we cast him out?

Bible References

Asked

Mark 4:10
And when he was alone they who were about him with the twelve questioned him as to the parables;
Matthew 13:10
And the disciples, coming near, said to him, Wherefore, in parables, art thou speaking to them?
Matthew 15:15
And Peter, answering, said unto him, Declare to us the parable.

Why

Matthew 17:19
Then, the disciples, coming near, to Jesus, privately, said - Wherefore could, we, not cast it out?

General references

2 Kings 20:10
And Hezekiah said - It is, a light thing, for the shadow, to decline ten steps, - Nay, but let the shadow go back ten steps.
Matthew 17:19
Then, the disciples, coming near, to Jesus, privately, said - Wherefore could, we, not cast it out?
Mark 10:10
And, coming into the house again, the disciples, concerning this, were questioning him;