And you shall take a bunch of hyssop, dip it in the blood that is in the basin, and strike the lintel and the two doorposts with the blood that is in the basin. And none of you shall go out of the door of his house until morning.
Exodus 12:22 NKJV
Some interesting observations on this verse.
This is a foreshadowing of the cross of Christ.
You needed to be inside, beyond the door, in the house in order to be safe. You had to trust and do what God said through His representative Moses.
The representative of the house would kill the lamb. Man in his sin killed Christ.
The blood of Christ and hyssop are symbols of spiritual cleansing.
The stains of blood would have been in the places where His hands and head would have been if on a cross.