זוהר שמות — דף לה ע”ב

The tortuous serpent is always crooked and brings curses upon the world. When this serpent rises, the dragon s power is broken. The Holy One bends the dragon into the sea and treads upon the power of the sea. The serpent of the land always prevails over the serpent of the sea. The blood of Passover on the lintel and two doorposts served to expel the spirit of impurity from among the Israelites. Egypt was full of idolatry and sorcery bound to the lower crowns. The bundle of hyssop dipped in blood was to expel the spirit of impurity.