Matthew 13:10
(And His disciples came and asked Him, "Why do you speak to them in figurative language?"
Mark 4:10
When He was alone, the Twelve and the others who were about Him requested Him to explain His figurative language.
Mark 4:33-34
With many such parables He used to speak the Message to them according to their capacity for receiving it.
Treasury of Scripture Knowledge
Summary
And the disciples came, and said unto him, Why speakest thou unto them in parables?