Matthew 13:10
And the disciples having come, they said to him, Why do thou speak to them in parables?
Mark 4:10
And when he became alone, those around him, with the twelve, asked him the parable.
Mark 4:33-34
And with many such parables he spoke the word to them, as they were able to hear it.
Treasury of Scripture Knowledge
Summary
And the disciples came, and said unto him, Why speakest thou unto them in parables?