Hyssop grew commonly on rocks and walls in the Near East and Egypt (v. 22). If it was the same plant that we identify as hyssop today, masses of tiny white flowers and a fragrant aroma characterized it. The Jews used it for applying blood to the door in the Passover ritual because of its availability and suitability as a liquid applicator. They also used it in the purification rite for lepers (Lev. 14:4, 6), the purification rite for a plague (Lev. 14:49-52), and for the red heifer sacrifice ritual (Num. 19:2-6).
"The hairy surface of its leaves and branches holds liquids well and makes it suitable as a sprinkling device for purification rituals."212
"The people were instructed that the only way they could avert the destroyer' was to put the blood of the lamb on their doorposts. Though the text does not explicitly state it, the overall argument of the Pentateuch . . . would suggest that their obedience to the word of the Lord in this instance was an evidence of their faith and trust in him [cf. Heb. 11:28]."213
God through Moses stressed the significance and the importance of perpetuating the Passover (v. 26).
"The Israelitish child will not unthinkingly practice a dead worship; he will ask: What does it mean? and the Israelitish father must not suppress the questions of the growing mind, but answer them, and thus begin the spiritualizing [the explanation of the spiritual significance] of the paschal rite."214
Worship and obedience occur together again here (vv. 27-28). These are the two proper responses to God's provision of redemption. They express true faith. These are key words in Exodus.
"The section closes with one of those rare notices in Israel's history: they did exactly what the Lord had commanded (v. 28)--and well they might after witnessing what had happened to the obstinate king and people of Egypt!"215