Exodus 7:1 - Joseph Benson’s Commentary on the Old and New Testaments

A god to Pharaoh That is, my representative in this affair, as magistrates are called gods, because they are God's vicegerents. He was authorized to speak and act in God's name, and endued with a divine power, to do that which is above the ordinary course of nature. And Aaron shall be thy prophet That is, he shall speak from thee to Pharaoh, as prophets do from God to the children of men. Thou shalt as a god inflict and remove the plagues, and Aaron as a prophet shall denounce them.