Context: The divinely appointed role of Moses, according to Old Testament history, was to deliver his people from their Egyptian bondage. His task, which seemed formidable to him, demanded that he leave his home of exile, the land of Midian, and directly confront the dreaded Pharaoh with the request that the Hebrews be given three days in which to draw apart from Egypt and worship their God. Pharaoh's contempt for such a request, however, led only to his increasing the burdens of the Hebrews. Nevertheless, Moses was commanded by God to go again before Pharaoh, requesting the release of his people. To convince Pharaoh of the divine origin of his mission, he performed a miracle. However, since the magicians of Egypt were able to perform the same act, Pharaoh was unmoved. Once again Moses was commanded to approach Pharaoh with his request, this time upon the banks of the Nile, where, to persuade the unsympathetic ruler, he was to perform his second miracle, turning the water of the sacred river into blood. God instructed Moses in what to say to Pharaoh:
And thou shalt say unto him, The Lord God of the Hebrews hath sent me unto thee, saying, Let my people go, that they may serve me in the wilderness: and, behold, hitherto thou wouldest not hear.