Pharaoh requested that Moses and Aaron perform a miracle to prove their divine authority since they claimed that God had sent them (vv. 9-10).
"What we refer to as the ten plagues' were actually judgments designed to authenticate Moses as God's messenger and his message as God's message. Their ultimate purpose was to reveal the greatness of the power and authority of God to the Egyptians (7:10-12:36) in order to bring Pharaoh and the Egyptians into subjection to God."121
The Jews preserved the names of the chief magicians even though the Old Testament did not record them. Paul said they were Jannes and Jambres (2 Tim. 3:9). These were not sleight-of-hand artists but wise men who were evidently members of the priestly caste (cf. Gen. 41:8). The power of their demonic gods lay in their "secret arts"(v. 11). They were able to do miracles in the power of Satan (1 Cor. 10:20; cf. Matt. 24:24; 2 Thess. 2:9-10; Rev. 13:13-14).122The superiority of the Israelites' God is clear in the superiority of Aaron's serpent over those of the Egyptian magicians (v. 12). The rod again represented regal authority and implied that Yahweh, not Pharaoh, was sovereign (cf. 4:2-5).
This miracle should have convinced Pharaoh of Yahweh's sovereignty, but he chose to harden his heart in unbelief and disobedience. Consequently God sent the plagues that followed.
"The point of this brief section is that Yahweh's proof of his powerful Presence to the Pharaoh and thus to the Pharaoh's Egypt will be miraculous in nature."123
