Exodus 12:12-13

And I shall pass through the land of Egypt in that night, and I shall smite all the first engendered or the first begotten things in the land of Egypt, from man till to beast; and I the Lord shall make dooms in all the gods of Egypt. Forsooth [the] blood shall be to you into sign, in the houses in which ye shall be; and I shall see the blood, and I shall pass over you; neither a wound destroying shall be in you, when I shall smite the land of Egypt.