4 God said to Moses, "Reach out and grab it by the tail." He reached out and grabbed it - and he was holding his staff again. 5 "That's so they will trust that God appeared to you, the God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob." 6 God then said, "Put your hand inside your shirt." He slipped his hand under his shirt, then took it out. His hand had turned leprous, like snow. 7 He said, "Put your hand back under your shirt." He did it, then took it back out - as healthy as before. 8 "So if they don't trust you and aren't convinced by the first sign, the second sign should do it. 9 But if it doesn't, if even after these two signs they don't trust you and listen to your message, take some water out of the Nile and pour it out on the dry land; the Nile water that you pour out will turn to blood when it hits the ground."
Matthew Henry's Commentary on Exodus 4:4-9
Commentary on Exodus 4:1-9
(Read Exodus 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.