Exodus 4:9

And it shall come to pass, if they will not believe also these two signs, neither hearken unto thy voice, that thou shalt take of the water of the river (Nile), and pour it upon the dry land; and the water which thou takest out of the river shall become blood upon the dry land. The Nile was given the veneration of a god in Egypt on account of the fact that the fertility of the entire country depended upon its annual overflow. If Moses, therefore. had the power to turn this water of blessing into blood, he commanded a power which exceeded that of Pharaoh: death and destruction upon the tyrants was in his hand. The same almighty power of God is able to deliver us from every evil work and to give us the possession of the saints in light.