Matthew 13:10
Now when his disciples came up to him, they said,
Mark 4:10
When he was alone his followers and the Twelve began asking about the parables.
Mark 4:33-34
With many such illustrations Jesus used to tell his message to people as far as they were able to receive it;
Treasury of Scripture Knowledge
Summary
And the disciples came, and said unto him, Why speakest thou unto them in parables?