Exodus 12:6-7

You shall keep it until the fourteenth day of the same month, then the whole assembly of the congregation of Israel is to slaughter it at twilight. Moreover, they shall take some of the blood and put it on the two doorposts and on the lintel [above the door] of the houses in which they eat it. [Matt 26:28; John 1:29; Heb 9:14]