When Moses and Aaron came to Pharaoh, they said to him: "Thus saith the Lord, the God of Israel, Let my people go" (Ex. 5:1), that they may serve Me. He said: I know not the Lord. "Who is the Lord, that I should hearken unto his voice to let Israel go? I know not the Lord, and moreover I will not let Israel go" (Ex. 5:2). Aaron cast down his rod, and it became a fiery serpent. The magicians also cast down their rods, and they became fiery serpents. The rod of Aaron ran and swallowed them up with their rods, as it is said, "And Aaron's rod swallowed up their rods" (Ex. 7:12).