Psalms 51:7,8

The verbs in these verses may be regarded as optatives (mayest thou purge me), but it is preferable to render them as futures: Thou shalt purge me … thou shalt wash me … thou shalt make me hear. They thus give utterance to the Psalmist's faith that God can and will cleanse and restore him. In Psalms 51:9 ff direct prayer is resumed by the imperative, as in Psalms 51:1.

The figurative language is borrowed from the ceremonial of the law. A bunch of hyssop, some common herb which grew upon walls (Tristram, Nat. Hist. of the Bible, p. 455), was used as a sprinkler, especially in the rites for cleansing the leper and purifying the unclean. (Exodus 12:22; Leviticus 14:4 ff; Numbers 19:6 ff, Numbers 19:18 ff; Hebrews 9:19.) Washing of the person and clothes regularly formed part of the rites of purification. The Psalmist is of course thinking of the inward and spiritual cleansing of which those outward rites were the symbol. He appeals to God Himself to perform the office of the priest and cleanse him from his defilement.

whiter than snow Cp. Isaiah 1:18, where this natural emblem of purity is contrasted with the scarlet of sin, suggested by the stains of blood upon the hands (Psalms 51:15). Terms usually applied to garments (Psalms 51:2 note) are transferred to the person. Cp. Revelation 3:4-5; Revelation 4:4; &c.

It is unnecessary to follow the Syr. in reading thou shalt satisfy me with joy(Psalms 90:14) for thou shalt make me hear joy, though the change would be a simple one. The language is still borrowed from the law. As the purification of the unclean was the prelude to his readmission to the gladness of the worship of the sanctuary (Psalms 42:4), so the cleansing of the Psalmist's heart will be the prelude to his restoration to that -joy of God's salvation" (Psalms 51:12), which he desires.

the bones which thou hast broken For the sense of God's displeasure had as it were crushed and shattered his whole frame. See note on Psalms 42:10, and cp. Psalms 32:3.