Verses 1-4
Psalm 51:1-19. On the occasion, compare 2 Samuel 11:12. The Psalm illustrates true repentance, in which are comprised conviction, confession, sorrow, prayer for mercy, and purposes of amendment, and it is accompanied by a lively faith.
A plea for mercy is a confession of guilt.
blot out — as from a register.
transgressions — literally, “rebellions” (Psalm 19:13; Psalm 32:1).
Verse 2
Wash me — Purity as well as pardon is desired by true penitents.
Verse 3
before me — Conviction precedes forgiveness; and, as a gift of God, is a plea for it (2 Samuel 12:13; Psalm 32:5; 1 John 1:9).
Verse 4
Against thee — chiefly, and as sins against others are violations of God‘s law, in one sense only.
that … judgest — that is, all palliation of his crime is excluded; it is the design in making this confession to recognize God‘s justice, however severe the sentence.
Verse 5-6
His guilt was aggravated by his essential, native sinfulness, which is as contrary to God‘s requisitions of inward purity as are outward sins to those for right conduct.
Verse 6
thou shalt make, etc. — may be taken to express God‘s gracious purpose in view of His strict requisition; a purpose of which David might have availed himself as a check to his native love for sin, and, in not doing so, aggravated his guilt.
truth … and … wisdom — are terms often used for piety (compare Job 28:28; Psalm 119:30).
Verses 7-12
A series of prayers for forgiveness and purifying.
Purge … hyssop — The use of this plant in the ritual (Exodus 12:22; Numbers 19:6, Numbers 19:18) suggests the idea of atonement as prominent here; “purge” refers to vicarious satisfaction (Numbers 19:17-20).
Verse 8
Make … joy — by forgiving me, which will change distress to joy.
Verse 9
Hide, etc. — Turn from beholding.
Verse 10
Create — a work of almighty power.
in me — literally, “to me,” or, “for me”; bestow as a gift, a heart free from taint of sin (Psalm 24:4; Psalm 73:1).
renew — implies that he had possessed it; the essential principle of a new nature had not been lost, but its influence interrupted (Luke 22:32); for Psalm 51:11 shows that he had not lost God‘s presence and Spirit (1 Samuel 16:13), though he had lost the “joy of his salvation” (Psalm 51:12), for whose return he prays.
right spirit — literally, “constant,” “firm,” not yielding to temptation.
Verse 12
free spirit — “thy” ought not to be supplied, for the word “free” is, literally, “willing,” and “spirit” is that of David. “Let a willing spirit uphold me,” that is, with a soul willingly conformed to God‘s law, he would be preserved in a right course of conduct.
Verse 13
Then — Such will be the effect of this gracious work.
ways — of providence and human duty (Psalm 18:21, Psalm 18:30; Psalm 32:8; Luke 22:32).
Verse 14
Deliver — or, “Free me” (Psalm 39:8) from the guilt of murder (2 Samuel 12:9, 2 Samuel 12:10; Psalm 5:6).
righteousness — as in Psalm 7:17; Psalm 31:1.
Verse 15
open … lips — by removing my sense of guilt.
Verse 16
Praise is better than sacrifice (Psalm 50:14), and implying faith, penitence, and love, glorifies God. In true penitents the joys of pardon mingle with sorrow for sin.
Verse 18
Do good, etc. — Visit not my sin on Thy Church.
build … walls — is to show favor; compare Psalm 89:40, for opposite form and idea.
Verse 19
God reconciled, material sacrifices will be acceptable (Psalm 4:5; compare Isaiah 1:11-17).