8 Then the Lord said to Moses and Aaron, 9 "Pharaoh will demand, 'Show me a miracle.' When he does this, say to Aaron, 'Take your staff and throw it down in front of Pharaoh, and it will become a serpent. '" 10 So Moses and Aaron went to Pharaoh and did what the Lord had commanded them. Aaron threw down his staff before Pharaoh and his officials, and it became a serpent!
Matthew Henry's Commentary on Exodus 7:8-10
Commentary on Exodus 7:8-13
(Read Exodus 7:8-13)
What men dislike, because it opposes their pride and lusts, they will not be convinced of; but it is easy to cause them to believe things they wish to be true. God always sends with his word full proofs of its Divine authority; but when men are bent to disobey, and willing to object, he often permits a snare to be laid wherein they are entangled. The magicians were cheats, trying to copy the real miracles of Moses by secret sleights or jugglings, which to a small extent they succeeded in doing, so as to deceive the bystanders, but they were at length obliged to confess they could not any longer imitate the effects of Divine power. None assist more in the destruction of sinners, than such as resist the truth by amusing men with a counterfeit resemblance of it. Satan is most to be dreaded when transformed into an angel of light.