Mat Matthew, chapter The Gospel According to Matthew, chapter 13
That's why I speak to them in illustrations. For even though they see, they don't see; and even though they hear, they don't hear; nor do they understand.13:13. Jesus was referencing the Old Testament here. It could be any of these: Deuteronomy 29:4, Isaiah 42:20, Jeremiah 5:21, Ezekiel 12:2.