The major point of the psalm seems to be that the wicked's prosperity is short-lived.
The psalm also contains a simple formula for achieving peace of mind in the face of the wicked’s prosperity: “fret not … neither be thou envious” (verse 1), “trust … do good” (verse 3), “delight thyself also in the LORD” (verse 4), “commit thy way … trust” (verse 5), “rest … wait patiently … fret not” (verse 7), “cease from anger … forsake wrath … fret not” (verse 8).
All of these exhortations urge the believer to confidently trust the LORD concerning the many of life’s problems.
The psalm concludes appropriately with an undying affirmation of faith and trust in the unchanging character of God.David mixes and matches 6 thoughts in order to advance his major message on the eventual arrival of divine justice.
1. An Introductory Overview (37:1-2).
2. An Initial Expansion (37:3-11).
3. Some Proverbial Perspectives (37:12-24).
4. An Initial Testimony (37:25-26).
5. A Final Expansion (compare verses 3-11 with 37:27-34).
6. A Final Testimony (compare verses 25-26 with 37:35-40).
Psalm 37:1 Fret not thyself because of evildoers, neither be thou envious against the workers of iniquity.
Psalm 37:2 For they shall soon be cut down like the grass, and wither as the green herb.
Psalm 37:4 Delight thyself also in the LORD; and He shall give thee the desires of thine heart.
John 15:7 If ye abide in Me, and My words abide in you, ye shall ask what ye will, and it shall be done unto you.
The key to this is abide.
If we are hid in Christ and He is uppermost in our thoughts and deeds, then He will give us the desires of our heart.
Psalm 37:8 Cease from anger, and forsake wrath: fret not thyself in any wise to do evil.
The Hebrew word translated “fret” is charah, which speaks of “growing warm and blazing up;”.
To fret or worry is to be concerned with things over which one has no control or ability to change.
Psalm 37:10 For yet a little while, and the wicked [shall] not [be]: yea, thou shalt diligently consider his place, and it [shall] not [be].
Psalm 37:20 But the wicked shall perish, and the enemies of the LORD [shall be] as the fat of lambs: they shall consume; into smoke shall they consume away.
Psalm 37:25 I have been young, and [now] am old; yet have I not seen the righteous forsaken, nor his seed begging bread.
The social condition of the Israelites....Though there were rich and poor among them, there could scarcely be any that were very poor.
Where there was a general obligation upon all well-disposed persons to lend to such as were in need, and no interest could be asked upon loans.
And in the year of jubilee all debts were remitted, and mortgaged lands returned to their original owners or their families.
Actual begging was scarcely possible, and at any rate could only be brought about by extreme and reckless misconduct (see Prov. 20:4).
Psalm 37:27 Depart from evil, and do good; and dwell for evermore.Psalm 37:35 I have seen the wicked in great power, and spreading himself like a green bay tree.
Psalm 37:39 But the salvation of the righteous [is] of the LORD: [He is] their strength in the time of trouble.
Psalm 37:40 And the LORD shall help them, and deliver them: He shall deliver them from the wicked, and save them, because they trust in Him.
But if we would be thus delivered, observe:
1. That we must not unthankfully fret at God's providence Ps 37:1.
2. We must "trust in the Lord and do good" Ps 37:3.
3. We must "delight ourselves in the Lord," and not place our contentment on earthly things Ps 37:4.
4. We must "commit our ways to God" Ps 37:5.
5. We must get patience and humble affections Ps 37:7-11.
6. We must be of upright conversation Ps 37:14.
7. We must be merciful Ps 37:25-26.
8. We must "speak righteous things," and get "the law into our hearts" Ps 37:30-31.
9. We must "keep our way," and "wait on God".
This Psalm very much reminds one in its construction of the sententious and pithy conciseness of the Book of Proverbs."
BooksOfTheBible/Charles Spurgeon
BooksOfTheBible/Charles Spurgeon

