And the Lord said unto Moses, "Pharaoh's heart is stubborn, he refuseth
to let the people go. Get thee unto Pharaoh in the morning; lo, he goeth
out unto the water; and thou shalt stand by the river's brink to meet
him; and the rod which was turned to a serpent shalt thou take in thine
hand. And thou shalt say unto him, 'The Lord, the 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 hast not hearkened. Thus
saith the Lord, In this thou shalt know that I am the Lord: behold, I
will smite with the rod that is in mine hand upon the waters which are
in the river and they shall be turned to blood. And the fish that is in
the river shall die, and the river shall be polluted; and the Egyptians
shall loathe to drink water from the river.'"