And Jesus knowing their thoughts said, Wherefore think ye evil in your hearts?

People's New Testament

9:4 Wherefore think ye evil in your hearts? They had said nothing aloud, but he read their hearts.

Matthew Henry's Concise Commentary

9:1-8 The faith of the friends of the paralytic in bringing him to Christ, was a strong faith; they firmly believed that Jesus Christ both could and would heal him. A strong faith regards no obstacles in pressing after Christ. It was a humble faith; they brought him to attend on Christ. It was an active faith. Sin may be pardoned, yet the sickness not be removed; the sickness may be removed, yet the sin not pardoned: but if we have the comfort of peace with God, with the comfort of recovery from sickness, this makes the healing a mercy indeed. This is no encouragement to sin. If thou bring thy sins to Jesus Christ, as thy malady and misery to be cured of, and delivered from, it is well; but to come with them, as thy darlings and delight, thinking still to retain them and receive him, is a gross mistake, a miserable delusion. The great intention of the blessed Jesus in the redemption he wrought, is to separate our hearts from sin. Our Lord Jesus has perfect knowledge of all that we say within ourselves. There is a great deal of evil in sinful thoughts, which is very offensive to the Lord Jesus. Christ designed to show that his great errand to the world was, to save his people from their sins. He turned from disputing with the scribes, and spake healing to the sick man. Not only he had no more need to be carried upon his bed, but he had strength to carry it. God must be glorified in all the power that is given to do good.