Exodus 7:9
When Pharaoh shall speak unto you, saying, Shew a miracle for you: then thou shalt say unto Aaron, Take thy rod, and cast it before Pharaoh, and it shall become a serpent. When Pharaoh shall speak unto you, saying, Shew a miracle for you: then thou shalt say unto Aaron, Take thy rod, and cast it before Pharaoh, and it shall become a serpent.
When Pharaoh demands a miracle, Aaron is to cast his rod down before him and it will become a serpent, and this is the first display of signs before Pharaoh. The sign is meant to show and confirm that God, the great I AM, sent and commissioned Moses and Aaron to demand Israel's release so Israel may serve Him. The rod becoming a serpent is a divine miracle by God's power, not by any human ability, skill, or influence of Moses or Aaron.
Aaron's serpent is real, while the magicians through satanic power only make their rods appear to become serpents. The magicians by Satan's aid with enchantments also turn rods into serpents, counterfeiting the sign with a like work. Aaron's rod swallows the magicians' rods, proving God's work superior to Satan's deceptive imitations. The sign begins the demonstration that Egypt's gods can neither protect the people nor save themselves, for the serpents the Egyptians worshiped are destroyed.
Because the magicians do a like work, Pharaoh dismisses the miracle as performed by magic and not by God's power. The sign does not soften Pharaoh's hard heart; it leaves him unmoved, increases his hatred of the Israelites, and makes him more determined to resist. God restrains Pharaoh from harming Moses and Aaron despite his resistance. God does not use that first display to deliver Israel immediately, but overrules events so Pharaoh's tyrannical spirit and God's power are more fully revealed, making the Israelites eager to leave Egypt and choose God's service. Later judgments give Pharaoh evidence that God, not magic, is at work.
Moses' work to break Israel's yoke of bondage prefigures Christ's first advent to break Satan's power over the human family and deliver those made captives by him. Satan knows Christ's mighty works and miracles will prove the Father sent Him and threaten his power over mankind, so he works through Pharaoh's magicians to harden Pharaoh against God's power, to stagger the faith of Moses and Aaron in the divine origin of their mission, and to keep Israel from release, with the two-fold purpose of destroying the influence of God's work through Moses then and reaching down through all ages to destroy faith in Christ's miracles. The magicians can imitate only a few of God's miracles, and God limits Satan and cuts off his channel of working.