He smote also all the firstborn in their land,.... Both of men and beasts; the firstborn of the king on the throne, and of the maidservant behind the mill, and of the captive in the dungeon; this was the last plague, and which prevailed upon the Egyptians to let Israel go, Exodus 11:5.
The chief of all their strength; or the first of their strength; the same in different words as before, their firstborn; see Genesis 49:3.