Adam Clarke on Mark 4:11

Unto you it is given to know - Γνωναι, to know, is omitted by ABKL, ten others, the Coptic, and one of the Itala. The omission of this word makes a material alteration in the sense; for without it the passage may be read thus: - To you the mystery of the kingdom of God is given; but all these things are transacted in parables to those without. Griesbach leaves it doubtful. And Professor White says, probabiliter delendum. I should be inclined to omit it, were it not found in the parallel passages in Matthew and Luke, in neither of whom it is omitted by any MS. or version. See the dissertation on parabolical writing at the end of Mat 13:58.