John Gill Commentary Luke 8:10

"And he said, Unto you it is given to know the mysteries of the kingdom of God: but to the rest in parables; that seeing they may not see, and hearing they may not understand." — Luke 8:10 (ASV)

And he said, to you it is given to know the mysteries of
the kingdom of God
The doctrines of the Gospel, which to have spiritual knowledge is a special and peculiar gift of God. The Vulgate Latin and Persic versions read, "the mystery", in the singular, as in Mark: "but to others in parables"; that is, the doctrines of the Gospel are delivered in a parabolical way to others; to such as "are without", as the Evangelist Mark expresses it, who are strangers and foreigners, and not children, who are not the favourites of heaven, and the disciples of Christ:

that seeing they might not see, and hearing, they might not
understand ;
what was delivered to them; see the following notes. (See Gill on Matthew 13:11) (See Gill on Matthew 13:12) (See Gill on Matthew 13:13)