on Psalms 51 :18
Do good in thy good pleasure unto Zion - This and the following verse most evidently refer to the time of the captivity, when the walls of Jerusalem were broken down, and the temple service entirely discontinued; and, consequently, are long posterior to the times of David. Hence it has been concluded that the Psalm was not composed by David, nor in his time and that the title must be that of some other Psalm inadvertently affixed to this. The fourth verse has also been considered as decisive against this title: but the note on that verse has considerably weakened, if not destroyed, that objection. I have been long of opinion that, whether the title be properly or improperly affixed to this Psalm, these two verses make no part of it: the subject is totally dissimilar; and there is no rule of analogy by which it can be interpreted as belonging to the Psalm, to the subject, or to the person. I think they originally made a Psalm of themselves, a kind of ejaculatory prayer for the redemption of the captives from Babylon, the rebuilding of Jerusalem, and the restoration of the temple worship. And, taken in this light, they are very proper and very expressive.
The Psalm 117:1-2 contains only two verses; and is an ejaculation of praise from the captives who had just then returned from Babylon. And it is a fact that this Psalm is written as a part of the cxvith in no less than thirty-two of Kennicott's and De Rossi's MSS.; and in some early editions. Again, because of its smallness, it has been absorbed by the cxviiith, of which it makes the commencement, in twenty-eight of Kennicott's and De Rossi's MSS. In a similar way I suppose the two last verses of this Psalm to have been absorbed by the preceding, which originally made a complete Psalm of themselves; and this absorption was the more easy, because, like the cxviith it has no title. I cannot allege a similar evidence relative to these two verses, as ever having made a distinct Psalm; but of the fact I can have no doubt, for the reasons assigned above. And I still think that Psalm is too dignified, too energetic, and too elegant, to have been the composition of any but David. It was not Asaph; it was not any of the sons of Korah; it was not Heman or Jeduthun: the hand and mind of a greater master are here.
on Psalms 51 :18
Do good in thy good pleasure unto Zion - From himself - his deep sorrow, his conscious guilt, his earnest prayer for pardon and salvation - the psalmist turns to Zion, to the city of God, to the people of the Lord. These, after all, lay nearer to his heart than his own personal salvation; and to these his thoughts naturally turned even in connection with his own deep distress. Such a prayer as is here offered he would also be more naturally led to offer from the remembrance of the dishonor which he had brought on the cause of religion, and it was natural for him to pray that his own misconduct might not have the effect of hindering the cause of God in the world. The psalms often take this turn. Where they commence with a personal reference to the author himself, the thoughts often terminate in a reference to Zion, and to the promotion of the cause of religion in the world.
Build thou the walls of Jerusalem - It is this expression on which De Wette, Doederlein, and Rosenmuller rely in proof that this psalm, or this portion of it, was composed at a later period than the time of David, and that it must have been written in the time of the captivity, when Jerusalem was in ruins. See the introduction to the psalm. But, as was remarked there, it is not necessary to adopt this supposition. There are two other solutions of the difficulty, either of which would meet all that is implied in the language.
(a) One is, that the walls of Jerusalem, which David had undertaken to build, were not as yet complete, or that the public works commenced by him for the protection of the city had not been finished at the time of the fatal affair of Uriah. There is nothing in the history which forbids this supposition, and the language is such as would be used by David on the occasion, if he had been actually engaged in completing the walls of the city, and rendering it impregnable, and if his heart was intensely fixed on the completion of the work.
(b) The other supposition is, that this is figurative language - a prayer that God would favor and bless his people as if the city was to be protected by walls, and thus rendered safe from an attack by the enemy. Such language is, in fact, often used in cases where it could not be pretended that it was designed to be literal. See Jde 1:20; Romans 15:20; 1 Corinthians 3:12; Galatians 2:18; Ephesians 2:22; Colossians 2:7.
on Psalms 51 :18
51:18 Good pleasure - Thy free and rich mercy. Build - Perfect the walls and buildings of that city, and especially let the temple be built, notwithstanding my sins.