4:6 His hand was leprous, as snow - For whiteness. This signified, That Moses, by the power of God, should bring sore diseases upon Egypt, that at his prayer they should be removed. And that whereas the Israelites in Egypt were become leprous, polluted by sin, and almost consumed by oppression, by being taken into the bosom of Moses they should be cleansed and cured.
4:1-9 Moses objects, that the people would not take his word, unless he showed them some sign. God gives him power to work miracles. But those who are now employed to deliver God's messages to men, need not the power to work miracles: their character and their doctrines are to be tried by that word of God to which they appeal. These miracles especially referred to the miracles of the Lord Jesus Christ. It belonged to Him only, to cast the power of the devil out of the soul, and to heal the soul of the leprosy of sin; and so it was for Him first to cast the devil out of the body, and to heal the leprosy of the body.
