Charles Ellicott Commentary Exodus 5:2

"And Pharaoh said, Who is Jehovah, that I should hearken unto his voice to let Israel go? I know not Jehovah, and moreover I will not let Israel go." — Exodus 5:2 (ASV)

Who is the Lord?—Heb., Who is Jehovah? If Jehovah was a name whose use had been laid aside, as the later chapters of Genesis seem to indicate, and which was revived by the scene at the burning bush, Pharaoh very probably had not heard of it.

That I should obey his voice.—The king means to say that, whoever Jehovah is, He can have no authority over him, as He is not one of his gods. The Egyptians were accustomed to the idea of local gods and quite expected every nation to have its own deity or several deities; but they regarded the power of each as circumscribed, certainly not extending beyond the race or nation to which the god belonged.