51:1 Have mercy upon me, O God, according to thy lovingkindness: according unto the multitude of thy tender mercies blot out my transgressions.
51:7 Purge me with hyssop, and I shall be clean: wash me, and I shall be whiter than snow.
This Psalm must ever be, in its successive steps, the mould of the experience of a sinning saint who comes back to full communion and service. The steps are:
(1) sin thoroughly judged before God (vs. 1-6);
(2) forgiveness and cleansing through the blood (v. 7.f.c.)
(3) cleansing (v. 7,1,c, to 10.) Cf John 13:4-10; Ephesians 5:26; 1 John 1:9.
(4) Spirit-filled for joy and power (vs. 11,12);
(5) service (v. 13);
(6) worship (vs 14-17);
(7) the restored saint in fellowship with God, not about self, but about the blessing of Zion. Personally, it was David's pathway to restored communion after his sin with Bathsheba. Dispensationally, it will be the pathway of returning Israel. Deuteronomy 30:1-10.
51:11 Cast me not away from thy presence; and take not thy holy spirit from me.
Hyssop was the little shrub 1 Kings 4:33 with which the blood and water of purification were applied. ; Leviticus 14:1-7; Numbers 19:1-19. Cleansing in Scripture is twofold:
(1) Of a sinner from the guilt of sin; the blood ("hyssop") aspect;
(2) of a saint from the defilement of sin--the water ("wash me") aspect;
(3) Under grace the sinner is purged by blood when he believes Matthew 26:28; Hebrews 1:3; 9:12; 10:14. Both aspects of cleansing, by blood and by water, are brought out in ; John 13:10; Ephesians 5:25,26.
"He that is bathed needeth not save to wash his feet"; "Christ loved the church and gave Himself for it redemption by "blood, "hyssop," the "bath"] that He might sanctify and cleanse "it with the washing by the word": answering to the "wash me" of verse 7.
No believer of this dispensation, aware of the promise of His abiding John 14:16 should pray, "Take not Thy Holy Spirit from me." Ephesians 4:30 but while Christian position is not found here, Christian experience in essence is.