John Calvin on Luke 6:8-12

Luke 6:8. But he knew their thoughts If Matthew states the truth, they had openly declared by their language what was in their minds; and therefore Christ replies not to their secret thoughts, but to express words. But both may be true, that they spoke plainly, and yet that Christ discerned their secret thoughts; for they did not openly avow their designs, and Matthew himself tells us that their question was intended to take Christ by surprise; and, consequently, Luke means nothing more than that Christ was aware of their insidious designs, though not expressed in words.