The upper door post - Or lintel, Exodus 12:23. This direction was understood by the Hebrews to apply only to the first Passover: it was certainly not adopted in Palestine. The meaning of the sprinkling of blood is hardly open to question. It was a representation of the offering of the life, substituted for that of the firstborn in each house, as an expiatory and vicarious sacrifice.
Related Commentaries of Exodus 12:7
Exodus 12:7
7 And they shall take of the blood, and strike it on the two side posts and on the upper door post of the houses, wherein they shall eat it.