The Pulpit Commentary
Have mercy upon me, O God, according to thy loving-kindness. It is observable that the whole psalm is addressed to God (Elohim), and not to Jehovah (the "Lord" in Psa_51:15 is Adonai), as though the psalmist felt himself unworthy to utter the covenant-name, and simply prostrated himself as a guilty man before his offended Maker. It is not correet to say that "loving-kindness implies a covenant" (Cheyne), since God is "good to all, and his tender mercies are over all his works" (Psa_145:9). According unto the multitude of thy tender mercies blot out my transgressions. David's first prayer is for pity; his second, to have his offences "blotted out," or "wiped out"—entirely removed from God's book (comp. Exo_32:32; Isa_43:25; Isa_44:22). He says "my transgressions," in the plural, because "his great sin did not stand alone—adultery was followed by treachery and murder" (Canon Cook).

The Pulpit Commentary
Wash me throughly from mine iniquity. Wash me, as a fuller washes a fouled garment (πλῦνον, LXX; not υίψον), not as a man washes his skin. And cleanse me from my sin. "Transgressions," "iniquity," "sin," cover every form of moral evil, and, united together, imply the deepest guilt (comp. Psa_51:3, Psa_51:5, Psa_51:9, Psa_51:14).

The Pulpit Commentary
For I acknowledge my transgressions (comp. Psa_32:5, "I said, I will confess my transgressions unto the Lord; and thou forgavest the iniquity of my sin"). The first step in repentance is contrition; the second, confession; the third, amendment of life. And my sin is ever before me. I bear it in mind; I do not hide it from myself. I keep it continually before my mental vision. This, too, is characteristic of true penitence. Mock penitents confess their sins, and straightway forget them. Real genuine ones find it impossible to forget.

The Pulpit Commentary
Against thee, thee only, have I sinned. Though no sins could be more directly against man than adultery and murder, yet David feels that that aspect of them shrinks away into insignificance, and is as if it were not, when they are viewed in their true and real character, as offences against the majesty of God. Every sin is mainly against God; and the better sort of men always feel this. "How can I do this great wickedness," says Joseph, when tempted by Potiphar's wife, "and sin against God?" And so David to Nathan, when he was first rebuked by him, "I have sinned against the Lord" (2Sa_12:13). And done this evil in thy sight; that thou mightest be justified when thou speakest, and be clear when thou judgest. Clear in the eyes of the world, that is; free from all charge of harshness or injustice, when thou judgest me, and condemnest me for my sins, as thou must do.

The Pulpit Commentary
The prayer now makes a stride in advance. It has been hitherto for the first step in justification—the wiping out of past transgressions. It is now for restoration, for a renewal of spiritual life, for a return to God's favour, and to the spiritual joy involved in it. First, however, an additional confession is made (Psa_51:5, Psa_51:6). Not only have I committed acts of sin (Psa_51:1-4), but sin is thoroughly ingrained into my nature. I was conceived in it; I was brought forth in it; only the strongest remedies can cleanse me from it (Psa_51:7). But cleansing alone is not enough. I need renewal (Psa_51:10); I need thy Holy Spirit (Psa_51:11); I crave, above all, the sense of a restoration to thy favour—a return to the old feelings of "joy and gladness" (Psa_51:8), even "the joy of thy salvation" (Psa_51:12).

Behold, I was shapen in iniquity; rather, in iniquity was I brought forth. And in sin did my mother conceive me. It is doubtless true, as Professor Cheyne says, that "the Old Testament contains no theory of the origin of sin"—no formulated doctrine on the subject. But the fact of congenital depravity is stated, not only here, but also in Job_14:4; Psa_58:3; it is also implied in Isa_43:27 and Hos_6:7.

The Pulpit Commentary
Behold, thou desirest truth in the inward parts (comp. Job_38:36). God requires not merely such purity as might be attained by the use of legal and ritual methods; but true inward purity of thought and heart, which is a very different matter. And in the hidden part thou shalt make me to know wisdom; rather, do thou make me. An optative, according to Professor Cheyne. The meaning is, "As nothing will content thee but this perfect, inward purity, do thou give me into my heart its fundamental principle-wisdom, or the fear of God."

The Pulpit Commentary
Purge me with hyssop, and I shall be clean. "Hyssop" alone could by the Levitical Law cleanse from contact with a corpse (Num_19:18) or from the defilement of leprosy (Le Psa_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" (Le Psa_14:6, Psa_14:7); 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 Psa_51:2).

The Pulpit Commentary
Make me to hear joy and gladness (comp. below, Psa_51:12). On forgiveness follows naturally the sense of it, and this sense is in itself a deep satisfaction. But the psalmist seems to ask for something more. He wants not mere negative peace and rest, but the active thrilling joy which those experience who feel themselves restored to God's favour, and bask in the light of his countenance. That the bones which thou hast broken may rejoice. That every ache and pain may cease, and be replaced by gladness and rejoicing.

The Pulpit Commentary
Hide thy face from my sins. Turn thyself away from them—do not so much as see them. The apostle speaks of times of ignorance, which God "winked at" (Act_17:30). And blot out all mine iniquities (comp. Psa_51:1).

The Pulpit Commentary
Create in me a clean heart, O God; i.e. do more than purify me—do more than cleanse me (Psa_51:7); by an act of creative power (בּרא) make in me a new clean heart. Compare the Christian doctrine of the "new birth" and "new life." And renew a right spirit within me. "Heart" and "spirit" are used interchangeably for the inward essence of man; but, as Professor Cheyne observes, "Heart emphasizes the individual side of a man's life; spirit, its Divine, or at least preternatural side." David, in asking both for a new heart and a new spirit, requests the renovation of his entire mental and moral nature, which he recognizes as corrupt and depraved.

The Pulpit Commentary
Cast me not away from thy presence. To he "cast away from God's presence" is to be altogether cast out of his covenant, made an alien from him, deprived of his favour and the light of his countenance (see Gen_4:14; 2Ki_13:23). The psalmist deprecates so terrible a punishment, although he feels that he has deserved it. And take not thy Holy Spirit from me. God's Holy Spirit had been poured upon David when he was first anointed by Samuel to the kingly office (1Sa_16:13). His great sins had undoubtedly "grieved" and vexed the Spirit; and, had they been continued or not repented of, would have caused him to withdraw himself; but they had not "wholly quenched the Spirit" (1Th_5:19). David was therefore able to pray, as he does, that the Holy Spirit of God might still be vouchsafed to him, and not be "taken away," as from one wholly unworthy.

The Pulpit Commentary
Restore unto me the joy of thy salvation. Give me back that "joy" which was mine when I was conscious of thy favour, and felt that thou wert my Strength and my Salvation (Psa_18:1; Psa_62:2, etc.). And uphold me with thy free spirit. There is no "thy" in the original; and it is his own spirit, not God's Spirit, of which the psalmist here speaks. "Uphold me," he says, "preserve me from falling, by giving me a 'free,' or 'generous,' or 'noble' spirit—the opposite of that 'spirit of bondage' which the apostle says that Christians do not receive" (Rom_8:15).

The Pulpit Commentary
The psalmist now turns from prayer to promise. If God will grant his petitions, restore him to favour, and renew his spiritual life, then he will make such return as is possible to him. First, he will teach transgressors God's ways (Psa_51:13). Next, he will extol his righteousness, and show forth his praise(Psa_51:14, Psa_51:15). Finally, he will offer him, not bloody sacrifice, but the sacrifice in which he delights—"the sacrifice of a broken spirit, a broken and contrite heart" (Psa_51:16, Psa_51:17). Such sacrifice, he is sure, God will not despise.

Then will I teach transgressors thy ways. The truly grateful heart cannot be satisfied without making some return to God for his goodness. The most satisfactory return is by deeds, not words. David's determination is to do his best to promote the glory of God by bringing others to salvation, turning them from their own evil ways to the "ways" that God would have them walk in. And sinners shall be converted unto thee. The result, he hopes, will be the conversion to God of many "sinners" (comp. Psa_32:8).

The Pulpit Commentary
Deliver me from bloodguiltiness, O God. In David's mouth this prayer is readily intelligible. In that of Babylonian exiles, the victims of oppression and wrong, it would be most extraordinary. Thou God of my salvation (comp. Psa_18:46; Psa_25:5; Psa_27:9 : Psa_88:1, etc.). And my tongue shall sing aloud of thy righteousness. In further acknowledgment of God's goodness, and as, in some sort, a return for it, David will employ himself in singing the praises of God (see his many psalms of praise) and will especially exalt God's righteousness. "Jehovah," as Professor Cheyne observes, "is equally righteous when he sends and when he removes chastisements."

The Pulpit Commentary
O Lord (not Jehovah, but Adonai), open thou my lips; and my mouth shall show forth thy praise. A sense of his guilt has long kept the psalmist's lips closed. Let his sins be forgiven, and his conscience relieved, then praise and thanksgiving will flow from his mouth freely and copiously.

The Pulpit Commentary
For thou desirest not sacrifice; else would I give it. If there had been any sacrifices which God desired or required for such offences as adultery and murder, David would have willingly offered them. But there were none. As Hammond observes, "The Mosaical Law allows no reconciliation, no sacrifice, for such sins." Thou delightest not in burnt offering. In the mere act of sacrifice—the untimely slaying of his own creatures—God could at no time have had any pleasure. His satisfaction could only arise from the spirit in which sacrifices were offered—the gratitude, devotion, self-renunciation, obedience, of those who approached him with them (comp. Psa_40:6; Psa_50:8-13; Isa_1:11-17, etc.).

The Pulpit Commentary
The sacrifices of God; i.e. the sacrifices which God really values and desires. Are a broken spirit: a broken and a contrite heart, O God, thou wilt not despise. "The contrite heart," says Hengstenberg, "denotes deep but soft and mild distress." It sets up no wild shriekings, no howls, like those of Oriental fanatics. But it nourishes a sorrow that is deep and persistent. The joy on account of forgiveness and restoration to favour does not exclude continued pain on account of past sin.

Psa_51:18, Psa_51:19

That this is an addition made to the original psalm, during the time of the Babylonian exile, or later, for liturgical purposes, has been maintained by a large number of the commentators who ascribe the rest of the psalm to David. The chief ground for the supposition is the prayer in Psa_51:18, "Build thou the walls of Jerusalem," which has been supposed to imply that the walls were in ruins, whereas under David they should have been, it is thought, in good condition. But it has been pointed out, very justly, that the fortifications of Jerusalem were not complete in David's time, and that both he and Solomon added considerably to them (2Sa_5:9; 1Ki_3:1; 1Ki_9:15, 1Ki_9:19). David may well have thought that, as a punishment for his sin, God might interfere with the work which he was doing for the benefit of his people, and hence have felt it needful to pray, "Do good unto Zion: build thou the wails of Jerusalem."

The Pulpit Commentary
Do good in thy good pleasure unto Zion. It is characteristic of David to pass from prayer for himself to prayer for the people committed to him, and especially to do so at or near the end of a psalm (see Psa_5:11, Psa_5:12; Psa_25:22; Psa_28:9; Psa_40:16). And he closely connects—nay, identifies—the people with their capital city (see Psa_46:4; Psa_48:11; Psa_69:35, etc.). Build thou the walls of Jerusalem. Josephus says that David encompassed the whole city of Jerusalem with walls ('Ant. Jud.,' 7.3, § 2); and we are told, in the Second Book of Samuel, that he "built round about from Mille and inward." It has been argued that his walls were just approaching their completion at the time of his great sin.

The Pulpit Commentary
Then shalt thou be pleased with the sacrifices of righteousness. "Then"—when the walls are completed—thou shalt receive the public sacrifices which will naturally be offered on the accomplishment of such a work (Neh_12:43). And these sacrifices, offered willingly by grateful hearts, will be pleasing and acceptable unto thee. With burnt offering, and whole burnt offering. Only the head, the fat, and certain portions of the interior were ordinarily burnt when a victim was offered (Le 1:8, 12; Psa_3:3, Psa_3:4, etc.); but sometimes, when the offerer's heart was full, and he desired to indicate its complete and undivided surrender to God, the entire victim was consumed (see Hengstenberg, ad loc.). Then shall they offer bullocks upon thine altar. Bullocks, or oxen, were offered on all great occasions (see 2Sa_24:22-25; 1Ki_8:63; 1Ch_29:21; 2Ch_7:5; 2Ch_29:32, 2Ch_29:33; 2Ch_35:7, 2Ch_35:9; Ezr_6:17, etc.).