Exodus 7:15-17

Darby Translation

¹⁵ Go unto Pharaoh in the morning—behold, he will go out unto the water—and take thy stand by the bank of the river in front of him; and take in thy hand the staff that was turned into a serpent.

¹⁶ And say unto him, Jehovah the God of the Hebrews has sent me to thee, saying, Let my people go, that they may serve me in the wilderness; but behold, hitherto thou hast not hearkened.

¹⁷ Thus saith Jehovah: In this shalt thou know that I am Jehovah—behold, I will smite with the staff that is in my hand upon the water which is in the river, and it shall be turned into blood.