This psalm is entitled simply "of David," or "by David" - לדוד ledâvid. In the original title there is no intheation, as in Psalm 3:1-8; Psalm 4:1-8; Ps. 7; Psalm 16:1-11; Psalm 17:1-15, whether it is a "psalm" or some other species of composition, but the idea is merely that it is a "composition" of David, or that David was its "author."
This is one of the "alphabetical" psalms: see introduction to Ps. 25. In this psalm the uniqueness of the composition is, that the successive letters of the alphabet occur at the beginning of every other verse, the first, the third, the fifth, etc. The exceptions are at Psalm 37:7, Psalm 37:20, Psalm 37:29, Psalm 37:34. In Psalm 37:29 the Hebrew letter צ (ts) occurs instead of the Hebrew letter ע (‛); and in Psalm 37:7, Psalm 37:20, Psalm 37:34, the letter introduces only a single verse. It is not possible now to account for these irregularities in the structure of the psalm. John John Bellermann (in dem Versuch uber die Metrik der Hebraer, p. 117ff) endeavored from conjecture to restore the regular series of verses by changing a portion of them; but there is no authority for this from the manuscripts, and the probability is, that the author of the psalm did not observe entire accuracy in this respect, but that he made use of the successive Hebrew letters only as a general guide in controlling the mode of the composition. In this psalm the succession of "letters" does not in any way denote a succession or a variety of "subjects."
The occasion on which the psalm was composed is not mentioned in the title, nor is there anything in the psalm itself to fix it to any particular period of the life of David. Like Ps. 73, it seems to have been suggested by a contemplation of the character and designs of the wicked, and especially of the fact that they are permitted to live, and that they enjoy, under the divine administration, so much prosperity. The psalm is designed to meet and remove the perplexity arising from that fact, not (it would seem) as a personal matter in the case of the psalmist, or because the author of the psalm was himself suffering any wrong from the wicked, but as a perplexity often arising from the general fact. This fact has perplexed and embarrassed reflecting men in all ages, and it has been an object of earnest solicitude to find a solution of it, or a method of reconciling it with the administration of a pure and righteous God. The purpose of this psalm seems to have been to furnish in some degree a solution of the difficulty, or to calm down the mind in its contemplation. The psalm begins, therefore, with the general counsel, "Fret not thyself because of evil doers, neither be thou envious against the workers of iniquity," Psalm 37:1. This may be regarded either as counsel addressed to some one - either a real or an imaginary person - whose mind was thus agitated, or who was disposed to fret and complain on account of this - and, on that supposition, the drift of the psalm is to calm down such a mind; or it may be regarded as the address or counsel of "God" directed to the psalmist himself in "his" state of perplexity and embarrassment on the subject. From some things in the psalm Psalm 37:25, Psalm 37:35-36 it seems most probable that the former is the true supposition.
The points in the psalm are the following:
I. The main subject of the psalm - the exhortation not to fret" or be troubled on account of evil-doers and the workers of iniquity; not to allow the mind to be anxious in regard to the fact that there are such persons, or in regard to their plans, or to their prosperity in the world - for they are soon to be cut down and pass away, Psalm 37:1-2.
II. The state of mind which should be cherished in such cases - "calm confidence in God in the faithful performance of duty," Psalm 37:3-8. We are to trust in the Lord, and do good, Psalm 37:3 to find our happiness in God, Psalm 37:4; to commit our way to Him in all our perplexities and troubles, Psalm 37:5-6; to rest secure in Him, waiting patiently for His interposition, Psalm 37:7; and to cease from all wrathful or revengeful feelings in reference to the wicked, Psalm 37:8.
III. The reasons for this state of mind, Ps. 37:9-40.
These reasons, without being kept entirely distinct, are two in number:
(1) The future doom of the Psalm 37:9-15. The general idea here is that they will be cut off, and soon pass away; that they will not secure ultimate success and prosperity, but that their wicked conduct will recoil on themselves, and overwhelm them in destruction.
(2) The ultimate prosperity of the righteous, Ps. 37:16-40. This is illustrated from various points of view, and with special reference to the experience of the psalmist. After some general statements in regard to the happy lot of the righteous Psalm 37:16-24, he refers to his own observation, during a long life, respecting the comparative effects of a wicked and a righteous course. This is shown in two respects:
(a) The protection and care of Providence over the righteous, Psalm 37:25-26. He says that he had been young, and that he was then an aged man, but that in his long life he had never seen the righteous forsaken, nor his children begging bread.
(b) The providence of God as against the wicked, Psalm 37:35-36. He says that he had seen the wicked man in great power, and flourishing like a tree, but he soon passed away, and could no more be found upon the earth.
The general argument in the psalm, therefore, is that righteousness, the fear of God, "religion," has a tendency to promote ultimate happiness, and to secure length of days and real honor upon the earth; that the prosperity of the wicked is temporary, and that however prosperous and happy they may seem to be, they will be ultimately cut off and made miserable.
It remains only to add that this psalm was composed when David was an old man Psalm 37:25; and apart, therefore, from the fact that it is the work of an inspired writer, it has special value as expressing the result of the observations of a long life on a point which perplexes the good in every age.

Godly directions for those who are in adversity not to envy the prosperity of the wicked, because it is superficial, and of short duration, vv. 1-22; to put their confidence in God, and live to his glory, as this is the sure way to be happy in this life, and in that which is to come, vv. 23-40.
In the title this Psalm is attributed to David by the Hebrew, and by most of the Versions: but it is more likely it was intended as an instructive and consoling ode for the captives in Babylon, who might feel themselves severely tempted when they saw those idolaters in prosperity; and themselves, who worshipped the true God, in affliction and slavery. They are comforted with the prospect of speedy deliverance; and their return to their own land is predicted in not less than ten different places in this Psalm.
This Psalm is one of the acrostic or alphabetical kind: but it differs from those we have already seen, in having two verses under each letter; the first only exhibiting the alphabetical letter consecutively. There are a few anomalies in the Psalm. The hemistich, which should begin with the letter ע ain, has now a ל lamed prefixed to the word with which it begins, לעולם leolam; and the hemistich which should begin with ת tau (Psalm 37:39) has now a ו vau prefixed, ותשועת utheshuath. It appears also that the letters ד daleth, כ caph, and ק koph, have each lost a hemistich; and ע ain, half a one. The manner ill which this Psalm is printed in Dr. Kennicott's Hebrew Bible gives a full view of all these particulars. To the English reader some slighter differences may appear; but it should be observed, that the verses in our English Bibles are not always divided as those in the Hebrew. In all the Psalm that have a title, the title forms the first verse in the Hebrew; but our translation does not acknowledge any of those titles as a part of the Psalm, and very properly leaves them out of the enumeration of the verses.

INTRODUCTION TO PSALM 37
A Psalm of David. This psalm, it is very probable, was written at the same time, and upon the same occasion, with the former; and describes the different states of good and bad men; and is full of exhortations, instructions, and advice to the people of God; intermixed with various encouraging promises. A late learned writer (h) thinks it was written for Mephibosheth's consolation under Ziba's calumny.
(h) Delaney's Life of King David, vol. 2. p. 219.

David persuades to patience and confidence in God, by the state of the godly and of the wicked.

The Seeming Prosperity of the Wicked, and the Real Prosperity of the Godly
The bond of connection between Psalm 36:1-12 and 37 is their similarity of contents, which here and there extends even to accords of expression. The fundamental thought running through the whole Psalm is at once expressed in the opening verses: Do not let the prosperity of the ungodly be a source of vexation to thee, but wait on the Lord; for the prosperity of the ungodly will suddenly come to an end, and the issue determines between the righteous and the unrighteous. Hence Tertullian calls this Psalm providentiae speculum; Isodore, potio contra murmur; and Luther, vestis piorum, cui adscriptum: Hic Sanctorum patientia est (Revelation 14:12). This fundamental thought the poet does not expand in strophes of ordinary compass, but in shorter utterances of the proverbial form following the order of the letters of the alphabet, and not without some repetitions and recurrences to a previous thought, in order to impress it still more convincingly and deeply upon the mind. The Psalm belongs therefore to the series Ps 9 and Psalm 10:1, Psalm 25:1, Psalm 34:1, - all alphabetical Psalm of David, of whose language, cheering, high-flown, thoughtful, and at the same time so easy and unartificial, and withal elegant, this Psalm is fully worthy. The structure of the proverbial utterances is almost entirely tetrastichic; though ד, כ, and ק are tristichs, and ח (which is twice represented, though perhaps unintentionally), נ, and ת are pentastichs. The ע is apparently wanting; but, on closer inspection, the originally separated strophes ס and ע are only run into one another by the division of the verses. The ע strophe begins with לעולם, Psalm 37:28, and forms a tetrastich, just like the ס. The fact that the preposition ל stands before the letter next in order need not confuse one. The ת, Psalm 37:39, also begins with ותשׁועת. The homogeneous beginnings, זמם רשׁע, לוה רשׁע, צופה רשׁע, Psalm 37:12, Psalm 37:21, Psalm 37:32, seem, as Hitzig remarks, to be designed to give prominence to the pauses in the succession of the proverbial utterances.