Matthew 13:10-17 (Also found in Mark 4:10-12 and Luke 8:9-10)
Disciples (to Jesus): Why do you speak to the people in parables?
Jesus: Because it is given to you to know the mysteries of the kingdom of heaven, but to them it is not given.
For whoever has, to him shall be given, and he shall have more abundance:
but whoever has not, from him shall be taken away even that which he has.
Therefore, I speak to them in parables: because seeing they see not; and hearing they hear not, neither do they understand.
In them is the prophecy of Isaiah fulfilled, which says,
By hearing you shall hear, and shall not understand; and seeing you shall see, and shall not perceive: Because this people’s heart is waxed gross, and their ears are dull of hearing, and their eyes they have closed; lest at any time they should see with their eyes, and hear with their ears, and should understand with their heart, and should be converted, and I should heal them. (Isaiah 6:9-10)
But blessed are your eyes, for they see: and your ears, for they hear.
I say to you, That many prophets and righteous men have desired to see those things which you see, and have not seen them; and to hear those things which you hear, and have not heard them.