John Gill Commentary Luke 8:9

"And his disciples asked him what this parable might be." — Luke 8:9 (ASV)

And his disciples asked him
That is, as Mark says, "when he was alone"; after the multitude were departed, and they were by themselves, it may be in some house with other disciples:

saying, what might this parable be ?
what is the sense and meaning of it? According to Matthew, they asked why he spoke in parables to the people; and to such a question the following words are a proper answer.