And it came to pass, that at midnight the Lord smote all the firstborn in the land of Egypt,.... The midnight of the fifteenth of Nisan, as the Targum of Jonathan, when fast asleep, and thoughtless of any danger; and it being at such a time must strike with a greater horror and terror, when sensible of the blow, which might be attended with a great noise, that might awaken the rest: from the firstborn of Pharaoh that sat on his throne; the heir to his crown, who was to have sat upon his throne, or already did, being taken a partner with him in it: unto the firstborn of the captive that was in the dungeon; or prison, that was grinding at the mill there, Exo 11:5 which was the work and business the prisoners were often put to, as appears from the case of Samson, Jdg 16:21, and all the firstborn of cattle; which were left of the other plagues, which had consumed great numbers of them.