Exodus 4:1-17
At Pharaoh’s court, Moses had been instructed in all the wisdom of the Egyptians. But He had not learned to know the "I am". The years spent in the royal palace have not done more to make him an instrument suitable for the deliverance of the people. The murder of the Egyptian has indeed shown the contrary. After the forty years in the school of Pharaoh, another forty years are necessary in the school of God, right away in Midian. The result is that Moses no longer has anything to make him feel proud of himself. Formerly "mighty in words and in deeds" (Acts 7:22), he now declares that he has no eloquence and puts aside all his personal abilities. But if he has rightly ceased to have confidence in himself, he does not yet have full confidence in God. He has to learn that when the Lord calls a man to service, He gives at the same time all the resources necessary for the accomplishment of it.
The rod changing itself into a serpent shows that if God allows Satan to act for a moment, He stays over him to annul his power. At the cross, Christ has triumphed over the powers of evil (Colossians 2:15). The hand put into the bosom (the heart: source of evil) which becomes leprous, then is made whole again, illustrates the power of God to take away the stain of sin.