This verse is often explained as a quotation from Isaiah 6:1–13. But it is more correct to say that it is a direct statement by Jesus in which he applies a passage from Isaiah 6. There is no formula indicating a quotation. Rather, two passages out of a larger whole in Isaiah are applied, and the sequence of hearing and seeing is reversed.1
12 so that “they may indeed see but not perceive, and may indeed hear but not understand, lest they should turn and be forgiven.”