What does Exodus 12:22 mean?
Prior to hearing from Moses (Exodus 12:21), Israel was given a command (Exodus 12:1–2) to prepare flawless lambs for sacrifice (Exodus 12:3–6). These were to be sacrificed at a certain time, and their blood applied to the doorways of each Israelite home (Exodus 12:7). This act symbolized the future ministry of Jesus Christ, who was also perfect, yet sacrificed to save others (1 Corinthians 5:6–8). His blood is the means by which those who trust in God can be saved from wrath (John 3:16–18, 36; 1 Peter 1:19). This passage offers more details.The plant commonly called "hyssop" today may not be the same as the one described with the Hebrew word 'ēzob'. At the least, the plant would be similar, having a flowering head ideal for painting or dripping liquids. Commentators differ on whether the "basin" mentioned here is the bowl used to catch the lamb's blood, or a depression near the threshold used to catch rainwater and debris. Taking blood from this and applying it to the horizontal and vertical posts of the door created a visual expression of faith in God. Some interpreters believe that the motion of applying blood with hyssop would have created a bloody cross on the door (Colossians 1:19–20).
The family observing Passover was to remain inside for the entire night. God is bringing terrible wrath on Egypt (Exodus 11:4–6). Only those homes marked with lamb's blood will be spared (Exodus 12:13).