This psalm bears to the closing part of Ps. 40 (Psalm 40:13-17, see the notes in the Introduction to that psalm) a resemblance similar to that between Psalm 14:1-7 and Psalm 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.

The psalmist prays for speedy deliverance, Psalm 70:1; prays against those who sought his life, Psalm 70:2, Psalm 70:3; and for the blessedness of those who sought God, Psalm 70:4; urges his speedy deliverance, Psalm 70:5.
The title in the Hebrew is, To the chief Musician, A Psalm of David, to bring to remembranee. There seems little sense in this title. It seems to intimate that the Psalm was written as a memorial that David had been in sore affliction, and that God had delivered him. So the Vulgate, Septuagint, Ethiopic, and Arabic. It is almost word for word the same with the five last verses of Psalm 40, to the notes on which the reader is referred.

INTRODUCTION TO PSALM 70
To the chief Musician, A Psalm of David, to bring to remembrance. This psalm, according to Kimchi, was composed by David when he fled from Saul, or from Absalom; so Theodoret; but if at either of those times, it is most likely to be the latter, since the following psalm, it is certain, was penned when he was an old man, Psalm 69:9; the word translated "to bring to remembrance" is thought, by Aben Ezra, to be the first word of some pleasant song; see Psalm 38:1. The Targum paraphrases it, to remember the use of the frankincense; alluding to Leviticus 2:2; Jarchi says it signifies prayer, and refers to Psalm 20:7, as instances of the use of the word in such a sense; and so this psalm is composed by the psalmist in a petitionary way, to put the Lord in remembrance of his afflictions, and of his promises of help and deliverance, which he prays for; see Psalm 132:1; and that he would avenge him on his enemies, and show respect to his friends; or it was written to refresh his own memory with his present state, and to put him in mind from whence he might expect help and salvation. The title of the psalm in the Arabic version is, and so in the Vulgate Latin, following the Septuagint,
"a remembrance that the Lord had saved him:''
and in the Syriac version,
"a psalm of David as to the letter, when he sent Joab to take Shemuah (Sheba), who rebelled; also a supplication of the righteous, and even of Christ himself.''
And seeing this follows upon the preceding, and may be reckoned an appendix to it, and there are some things in it which manifestly refer to the latter part of that, and the whole is detached from the fortieth psalm, with which it agrees, a few words only excepted, which manifestly belongs to the Messiah; it is right to understand this of him; Psalm 40:13.

The speedy destruction of the wicked, and the preservation of the godly.

Cry of a Persecuted One for Help
This short Psalm, placed after Ps 69 on account of the kindred nature of its contents (cf. more especially v. 6 with Psalm 69:30), is, with but few deviations, a repetition of Psalm 40:14. This portion of the second half of Ps 40 is detached from it and converted into the Elohimic style. Concerning להזכּיר, at the presentation of the memorial portion of the mincha, vid., Psalm 38:1. It is obvious that David himself is not the author of the Psalm in this stunted form. The לדוד is moreover justified, if he composed the original Psalm which is here modified and appropriated to a special liturgical use.