'Door posts' in the Bible

They must take some of the blood and put it on the two doorposts and the lintel of the houses where they eat them.

Take a cluster of hyssop, dip it in the blood that is in the basin, and brush the lintel and the two doorposts with some of the blood in the basin. None of you may go out the door of his house until morning.

When the Lord passes through to strike Egypt and sees the blood on the lintel and the two doorposts, He will pass over the door and not let the destroyer enter your houses to strike you.