Exodus 12

12 And I will go through the land of Egypt in that night, and smite all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am Jehovah. 13 And the blood shall be for you as a sign on the houses in which ye are; and when I see the blood, I will pass over you; and the plague shall not be among you for destruction, when I smite the land of Egypt.