What does Exodus 12:21 mean?
So far, this chapter has contained the Lord's instructions as relayed to Moses and Aaron (Exodus 12:1). Some of those directions involved days of preparation (Exodus 12:3, 6). Moses appears to speak these words on the day assigned for sacrifice. Rather than trying to address the entire nation at once, he passes the instructions through the nation's elders (Exodus 4:29–31). The people were to follow God's commands to sacrifice lambs and apply the blood to the doorways of their homes (Exodus 12:7). This would be the sign by which God would "pass over" that home (Exodus 12:13) when bringing His judgment on Egypt (Exodus 11:4–6).Upcoming verses will further explain how this blood is to be applied. Using hyssop—a plant well suited to smearing or dripping liquids—the lamb's blood was to be applied to the top beam and side posts of the door (Exodus 12:22). Depending on how this is done, such application could create a bloody cross on the door itself (1 Corinthians 5:6–8). The people were to remain behind that symbol of protection overnight while the Lord judged Egypt (Exodus 11:4–6).