Fear had caused Moses to hesitate to obey God from the beginning so when he did obey God, Pharaoh's adamant refusal to listen reinforced Moses' fear. Immediately, Moses blamed the One who had issued the initial command. Fear is the reason that both Aaron and Moses are stubborn and reluctant to obey God. The task was an enormous one and these two Hebrews were often overcome with fear and doubt. God had to command Moses and Aaron because of the importance of the mission. God did not want cowards and doubters to stand before the great Pharaoh. He wanted strong men full of faith in the power of God.