“Since the world began was it not heard that any man opened the eyes of one that was born blind. If this man were not of God, he could do nothing.” - John 9:32-33.
As Jesus Christ was carrying out his work, he saw a man who was blind from his birth. Because a number of the Jews had a wrong notion that people's ailments or difficulties in life were due to their sins or that of their parents, they asked Jesus Christ whether the man's blindness was due to the sins of his parents or his own sins. Christ told them that neither was the case “but that the works of God should be made manifest in him” (John 9:3). In other words, God allowed the man's affliction which was brought about by the devil so that he would show His power in due course and thereby inspire people to righteousness. Christ did not give a command for the man to be healed rather, he spat on the ground and made clay with it and rubbed on the man's eyes, he then told him to go and wash in the pool of Siloam.
The man went as he was commanded and came back seeing. His recovery of sight caused no small stir among the people for which cause, they pestered him with questions as to how he recovered his sight. He then made the famous words recorded in John 9: 31 to wit: “Now we know that God heareth not sinners: but if any man be a worshipper of God, and doeth his will, him he heareth.” See also 1 John 3:22.