Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
This psalm bears to the closing part of Ps. 40 (Psa 40:13-17, see the notes in the Introduction to that psalm) a resemblance similar to that between Psa 14:1-7 and Psa 53:1-6. The one is not indeed a mere copy of the other, but the one is substantially the same as the other, with some slight variations, apparently introduced to fit it for some new occasion on which it was to be used. We do not know what the occasion in either case was; but it would seem that in this instance, the psalmist found, in the closing verses of the fortieth psalm, language which "very nearly" expressed what he felt on some particular occasion, and which might, by a slight change, be applied to the use for which it was then desired.
We have no further knowledge of the "occasion" on which this was done, than what is implied in the title: "to bring to remembrance." For the meaning of this, see thenotes at the title to Ps. 38. It determines nothing, however, as to the reason why the closing part of Ps. 40 was selected as the subject of a separate psalm, or why the changes were made which here occur. It merely denotes that there were things which it was proper to preserve in the recollection; or principles which it was of importance for the people of God to remember.
It will be necessary, in considering the psalm, only to note, in each verse successively, the alterations which are made from Ps. 40.
Make haste - These words are supplied by our translators. The first word in Psa 40:13, rendered "be pleased," is here omitted in the original. The psalm in the Hebrew begins abruptly - "O God, to deliver me," - leaving the impression that this is a fragment - a fragment commencing without even the care necessary to make the grammatical construction complete.
O God - Hebrew, אלהים 'Elohiym. In the corresponding place in Psa 40:13 the word is "Yahweh." Why the change was made is unknown. The remainder of the verse is the same as in Ps. 40.
Let them be ashamed and confounded that seek after my soul - The only change here from Psa 40:14, is the omission of the word "together" which occurs there, and the omission of the words "to destroy it."
Let them be turned backward, and put to confusion, that desire my hurt - This corresponds in the Hebrew entirely with Psa 40:14.
Let them be turned back for a reward of their shame - The only change which occurs in this verse is the substitution of the milder phrase "Let them be turned back," for "Let them be desolate." See the notes at Psa 40:15.
Let all those that seek thee ... - The only change in this verse from Psa 40:16, is in the insertion of the word "and" in the beginning of the second clause - "and let such as love," etc.
But I am poor and needy - This is the same as in Psa 40:17.
Make haste unto me, O God - Hebrew, אלהים 'Elohiym. In the parallel place in Psa 40:17, this is, "The Lord thinketh upon me," - where the Hebrew word is not אלהים 'Elohiym, but אדני tub ,my 'Adonāy (Lord). The word "make haste" seems to have been introduced here by design - thus carrying out the main idea in Ps. 40, but turning here to "petition" what is there stated as a "fact."
Thou art my help and my deliverer ... - The close of the psalm is the same as the close of Ps. 40, except that the word Lord (Yahweh) is used here instead of "God" (אלהים 'Elohiym). It is not possible to ascertain whether these changes were mere matters of taste, or whether they were designed to adapt the psalm to some new circumstance, or to the special feelings of the psalmist at the time. There is no evidence that they are mere errors of transcribers, and indeed the changes are so made that this cannot be supposed. The change of the names אלהים 'Elohiym, יהוה Yahweh, and אדני 'Adonāy, for example, is such as must have been by design, and could not have been made by copyists. But what that design was must remain unknown. The alterations do not in any way, as far as we can understand, affect the sense.