Surah 7. Al-A'raf, Ayah 107

The serpent played a large part in Egyptian mythology. The great sun-god Ra won a great victory over the serpent Apophis, typifying the victory of light over darkness. Many of their gods and goddesses took the forms of snakes to impress their foes with terror. Moses's rod as a type of a serpent at once appealed to the Egyptian mentality. The contempt which the Egyptians had entertained in their minds before was converted into terror. Here was some one who could control the reptile which their great god Ra himself had such difficulty in overcoming!