(7) Hyssop.--The mention of this connects this verse with the priestly ordinances concerning leprosy and contact with a dead body (Leviticus 14; Numbers 19); but generally it is a repetition of the former prayer to have the breach made in the covenant - relationship healed. (Comp. Isaiah 1:18.)

Verse 7. - Purge me with hyssop, and I shall be clean. "Hyssop" alone could by the Levitical Law cleanse from contact with a corpse (Numbers 19:18) or from the defilement of leprosy (Leviticus 14:4). David recognizes that his impurity is of the extremest kind, and needs the remedy which has the greatest purifying power. Legally, this was the hyssop, with its "blood of sprinkling" (Leviticus 14:6, 7); spiritually, it was the blood of Christ, which was thus symbolized. Wash me, and I shall be whiter than snow. Again the word is used which corresponds to the Greek πλῦνον. "Wash me as garments are washed by the fuller" (see the comment on ver. 2).

51:7-15 Purge me with hyssop, with the blood of Christ applied to my soul by a lively faith, as the water of purification was sprinkled with a bunch of hyssop. The blood of Christ is called the blood of sprinkling, Heb 12:24. If this blood of Christ, which cleanses from all sin, cleanse us from our sin, then we shall be clean indeed, Heb 10:2. He asks not to be comforted, till he is first cleansed; if sin, the bitter root of sorrow, be taken away, he can pray in faith, Let me have a well-grounded peace, of thy creating, so that the bones broken by convictions may rejoice, may be comforted. Hide thy face from my sins; blot out all mine iniquities out of thy book; blot them out, as a cloud is blotted out and dispelled by the beams of the sun. And the believer desires renewal to holiness as much as the joy of salvation. David now saw, more than ever, what an unclean heart he had, and sadly laments it; but he sees it is not in his own power to amend it, and therefore begs God would create in him a clean heart. When the sinner feels this change is necessary, and reads the promise of God to that purpose, he begins to ask it. He knew he had by his sin grieved the Holy Spirit, and provoked him to withdraw. This he dreads more than anything. He prays that Divine comforts may be restored to him. When we give ourselves cause to doubt our interest in salvation, how can we expect the joy of it? This had made him weak; he prays, I am ready to fall, either into sin or into despair, therefore uphold me with thy Spirit. Thy Spirit is a free Spirit, a free Agent himself, working freely. And the more cheerful we are in our duty, the more constant we shall be to it. What is this but the liberty wherewith Christ makes his people free, which is contrasted with the yoke of bondage? Ga 5:1. It is the Spirit of adoption spoken to the heart. Those to whom God is the God of salvation, he will deliver from guilt; for the salvation he is the God of, is salvation from sin. We may therefore plead with him, Lord, thou art the God of my salvation, therefore deliver me from the dominion of sin. And when the lips are opened, what should they speak but the praises of God for his forgiving mercy?Purge me with hyssop,.... Or "thou shalt purge me with hyssop" (f); or "expiate me"; which was used in sprinkling the blood of the paschal lamb on the door posts of the Israelites in Egypt, that the destroying angel might pass over them, Exodus 12:22; and in the cleansing of the leper, Leviticus 14:4; and in the purification of one that was unclean by the touch of a dead body, &c. Numbers 19:6; which the Targum on the text has respect to; and this petition of the psalmist shows that he saw himself a guilty creature, and in danger of the destroying angel, and a filthy creature like the leper, and deserving to be excluded from the society of the saints, and the house of God; and that he had respect not hereby to ceremonial sprinklings and purifications, for them he would have applied to a priest; but to the sprinkling of the blood of Christ, typified thereby; and therefore he applies to God to purge his conscience with it; and, as Suidas (g) from Theodoret observes, hyssop did not procure remission of sins, but has a mystical signification, and refers to what was meant by the sprinkling of the blood of the passover; and then he says,

and I shall be clean; thoroughly clean; for the blood sprinkled on the heart by the spirit clears it from an evil conscience, purges the conscience from dead works, and cleanses from all sin;

wash me; or "thou shall wash me" (h); alluding to the washing at the cleansing of a leper, and the purification of an unclean person, Leviticus 14:8; but had in view the fountain of Christ's blood, in which believers are washed from all their sins, Zechariah 13:1;

and I shall be whiter than snow; who was black with original corruption, and actual transgressions; but the blood of Christ makes not only the conversation garments white that are washed in it; but even crimson and scarlet sins as white as wool, as white as snow, and the persons of the saints without spot or blemish, Revelation 7:14, Ephesians 5:25; "whiter than the snow" is a phrase used by Homer (i), and others, to describe what is exceeding white.

(f) "purificabis me", Pagninus, Montanus; "exiabis me", Vatablus, Musculus, Cocceius, Gejerus. (g) In voce (h) "lavabis me", V. L. Pagninus, Montanus, Vatablus, Musculus, Cocceius. (i) Iliad. 10. v. 437. So Martial. l. 7. Epigr. 27. Ovid. Amor. l. 3. Eleg. 6.