Exodus 5:1-3

And afterward Moses and Aaron came, and said unto Pharaoh, Thus saith Jehovah, the God of Israel, Let my people go, that they may hold a feast unto me in the wilderness. 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. And they said, The God of the Hebrews hath met with us: let us go, we pray thee, three days’ journey into the wilderness, and sacrifice unto Jehovah our God, lest he fall upon us with pestilence, or with the sword.