Hyssop in the Bible

Exodus 12:21 Then Moses called for all the elders of Israel, and said to them, “Draw out, and take lambs according to your families, and kill the Passover. 22 You shall take a bunch of hyssop, and dip it in the blood that is in the basin, and strike the lintel and the two doorposts with the blood that is in the basin; and none of you shall go out of the door of his house until the morning. (All Bible quotations from the World English Bible, public domain)

Leviticus 14:2 “This shall be the law of the leper in the day of his cleansing. He shall be brought to the priest, 3 and the priest shall go forth out of the camp. The priest shall examine him, and behold, if the plague of leprosy is healed in the leper, 4 then the priest shall command them to take for him who is to be cleansed two living clean birds, and cedar wood, and scarlet, and hyssop. 5 The priest shall command them to kill one of the birds in an earthen vessel over running water. 6 As for the living bird, he shall take it, and the cedar wood, and the scarlet, and the hyssop, and shall dip them and the living bird in the blood of the bird that was killed over the running water. 7 He shall sprinkle on him who is to be cleansed from the leprosy seven times, and shall pronounce him clean, and shall let the living bird go into the open field.

Leviticus 14:33 Yahweh spoke to Moses and to Aaron, saying, 34 “When you have come into the land of Canaan, which I give to you for a possession, and I put a spreading mildew in a house in the land of your possession, 35 then he who owns the house shall come and tell the priest, saying, ‘There seems to me to be some sort of plague in the house.’ . . . 48 “If the priest shall come in, and examine it, and behold, the plague hasn’t spread in the house, after the house was plastered, then the priest shall pronounce the house clean, because the plague is healed. 49 To cleanse the house he shall take two birds, and cedar wood, and scarlet, and hyssop. 50 He shall kill one of the birds in an earthen vessel over running water. 51 He shall take the cedar wood, and the hyssop, and the scarlet, and the living bird, and dip them in the blood of the slain bird, and in the running water, and sprinkle the house seven times. 52 He shall cleanse the house with the blood of the bird, and with the running water, with the living bird, with the cedar wood, with the hyssop, and with the scarlet;

Numbers 19:1 Yahweh spoke to Moses and to Aaron, saying, 2 “This is the statute of the law which Yahweh has commanded: Speak to the children of Israel, that they bring you a red heifer without spot, in which is no blemish, and which was never yoked. 3 You shall give her to Eleazar the priest, and he shall bring her forth outside of the camp, and one shall kill her before his face: 4 and Eleazar the priest shall take of her blood with his finger, and sprinkle her blood toward the front of the Tent of Meeting seven times. 5 One shall burn the heifer in his sight; her skin, and her flesh, and her blood, with her dung, shall he burn: 6 and the priest shall take cedar wood, and hyssop, and scarlet, and cast it into the midst of the burning of the heifer. 7 Then the priest shall wash his clothes, and he shall bathe his flesh in water, and afterward he shall come into the camp, and the priest shall be unclean until the evening. 8 He who burns her shall wash his clothes in water, and bathe his flesh in water, and shall be unclean until the evening.

Numbers 19:16 “Whoever in the open field touches one who is slain with a sword, or a dead body, or a bone of a man, or a grave, shall be unclean seven days. 17 “For the unclean they shall take of the ashes of the burning of the sin offering; and running water shall be put thereto in a vessel: 18 and a clean person shall take hyssop, and dip it in the water, and sprinkle it on the tent, and on all the vessels, and on the persons who were there, and on him who touched the bone, or the slain, or the dead, or the grave:

1 Kings 4:30 Solomon’s wisdom excelled the wisdom of all the children of the east, and all the wisdom of Egypt. 31 For he was wiser than all men; than Ethan the Ezrahite, and Heman, and Calcol, and Darda, the sons of Mahol: and his fame was in all the nations all around. 32 He spoke three thousand proverbs; and his songs were one thousand five. 33a He spoke of trees, from the cedar that is in Lebanon even to the hyssop that springs out of the wall;

Psalm 51:1 Have mercy on me, God, according to your loving kindness.
    According to the multitude of your tender mercies, blot out my transgressions. 
2 Wash me thoroughly from my iniquity.
    Cleanse me from my sin. 
3 For I know my transgressions.
    My sin is constantly before me. 
4 Against you, and you only, have I sinned,
    and done that which is evil in your sight;
that you may be proved right when you speak,
    and justified when you judge. 
5 Behold, I was brought forth in iniquity.
    In sin my mother conceived me. 
6 Behold, you desire truth in the inward parts.
    You teach me wisdom in the inmost place.
7 Purify me with hyssop, and I will be clean.
    Wash me, and I will be whiter than snow.

John 19:28 After this, Jesus, seeing that all things were now finished, that the Scripture might be fulfilled, said, “I am thirsty.” 29 Now a vessel full of vinegar was set there; so they put a sponge full of the vinegar on hyssop, and held it at his mouth. 30 When Jesus therefore had received the vinegar, he said, “It is finished.” He bowed his head, and gave up his spirit.

Hebrews 9:18 Therefore even the first covenant has not been dedicated without blood. 19 For when every commandment had been spoken by Moses to all the people according to the law, he took the blood of the calves and the goats, with water and scarlet wool and hyssop, and sprinkled both the book itself and all the people, 20 saying, “This is the blood of the covenant which God has commanded you.”

The quotations above include most or all of the Biblical references to hyssop. Just from reading them, it seems clear that it had ritual uses in purifying, persons, houses, the nation as a whole, and other things. We aren't told why hyssop, but it seems to be a reasonable guess that its leaves, or stems, or both were able to retain fluid, at least blood fluid, fairly well. The Wikipedia article on hyssop tells us that we aren't sure what kind of plant it is, or was. There is uncertainty about the identity of almost all of the plants mentioned in the Bible, which is not surprising, since, in English, at least, it is common for one species of plant to have more than one common name.

We don't need hyssop for cleansing, as we are now under the second covenant, but we do need cleansing, and should welcome it, even if it is painful. Thanks for reading.