What was hyssop and where did it grow in Egypt?
Hyssop was a little bush or weed that grew everywhere in Goshen, Egypt. It was so common that no Israelite could claim they lacked access to it. It was used to dip in the lamb's blood and apply it to the doorposts and lintel.
Les explains that hyssop was a little bush or a little weed that grew everywhere in Goshen. He likens it to ragweed in our part of the world—every place you look, there it is unless rooted out. The Israelites were to take a bunch of hyssop, dip it in the blood in the basin, and strike the lintel and the two sideposts. Les also likens hyssop to the work of the Holy Spirit, who is omnipresent and works on every human being. Just as hyssop was everywhere so no Israelite could say they had no chance, no one can say the Holy Spirit never worked in their life.
And ye shall take a bunch of hyssop, and dip it in the blood that is in the bason, and strike the lintel and the two side posts with the blood that is in the bason; and none of you shall go out at the door of his house until the morning.