R.Louis Ginzberg wrote in his book, Legends of the Jews 3:1:28-71
(40) ..... and I sent Moses and Aaron, My faithful messengers, to Pharaoh. When they came before the king of Egypt, they spake to him, 'Thus said the Lord, the God of Israel, Let My people go, that they may hold a feast unto Me in the wilderness.' In the presence of the kings of the East and of the West, the sinner began to boast, saying: 'Who is the Lord, that I should hearken unto His voice, to let Israel go? Why comes He not before me, like all the kings of the world, and why doth He not bring me a present like the others? This God of whom you speak, I know Him not at all. Wait and let me search my lists, and see whether I can find His Name.' But his servants said, 'We have heard that He is the son of the wise, the son of ancient kings.' Then Pharaoh asked My messengers, 'What are the works of this God?' and they replied, 'He is the God of gods, the Lord of lords, who created the heaven and the earth.' But Pharaoh doubted their words, and said, 'There is no God in all the world that can accomplish such works besides me, for I made myself, and I made the Nile river.
well, I read several midrash that mention that the pharaoh of Moses believed himself to be god. according to the passage of R.Louis Ginzberg, Pharaoh said: (There is no God in all the world that can accomplish such works" created the heaven and the earth" besides me, for I made myself)
Does anyone know where this specific Midrashic Passage can be found?