Psalm 37:7-8

ADAM CLARKE'S BIBLE COMMENTARY
Verse 7. "Rest in the Lord " - mwd dom, "be silent, be dumb." Do not find fault with thy Maker; he does all things well for others, he will do all things well for thee.
"And wait patiently for him " - wl llwjthw vehithcholel lo, and set thyself to expect him; and be determined to expect, or wait for him. Such is the import of a verb in the hithpoel conjugation.
"A heathen gives good advice on a similar subject: " - Nil ergo optabunt homines? Si consilium vis, Permittes ipsis expendere Numinibus, quid Conveniat nobis, rebusque sit utile nostris. Nam pro jucundis aptissima quaeque dabunt Di. Carior est illis homo, quam sibi. Juv. Sat. x. 346.
"What then remains? Are we deprived of will? Must we not wish, for fear of wishing ill? Receive my counsel, and securely move; Intrust thy pastime to the powers above. Leave them to manage for thee, and to grant What their unerring wisdom sees thee want. In goodness, as in greatness, they excel: Ah, that we loved ourselves but half so well!" DRYDEN.

Coffman's Commentaries on the Bible

Verse 8
REASONS FOR NOT FRETTING OVER EVIL-DOERS

"Cease from anger, and forsake wrath:
Fret not thyself, it tendeth only to evil-doing.
For evil-doers shall be cut off;
But those that wait for Jehovah, they shall inherit the land.
For yet a little while, and the wicked shall not be:
Yea, thou shalt diligently consider his place, and he shall not be.
But the meek shall inherit the land,
And shall delight themselves in the abundance of peace."
"Yet a little while, and the wicked shall be cut off" (Psalms 37:9), There is very likely a double meaning here. A lifetime on this earth is indeed a very brief time; and that fact is surely in view here; but the whole period of probation of mankind, which is concurrently extensive with the Christian dispensation is also but "a little time." The Lord has told us through the apostle John, that "The devil has great wrath (against mankind), knowing that he hath but a short time" (Revelation 12:12).
"And he shall not be" (Psalms 37:10). The marginal reading is that, "It shall not be," meaning that the place of the wicked shall not be found. Without this change, the meaning is simply that, "He (the wicked) shall not be found in his place."
"They shall inherit the land" (Psalms 37:9) The meek shall inherit the earth (v. 11). It should be noted that we have substituted the word "earth" for "land" in Psalms 37:11, for two reasons: (1) The Septuagint (LXX) renders it "earth"; and when Jesus Christ quoted from this chapter, he deliberately chose the reading, "The meek shall inherit the earth" (Matthew 5:5). It is our opinion that the preference of the Blessed Saviour should be allowed here (and everywhere, for that matter). It could not possibly have been an accident that Jesus used the word "earth." The Septuagint (LXX) has "land" in Psalms 37:9, and `earth' in Psalms 37:11; and Christ obviously, therefore, deliberately selected the correct rendition
It is not true that the "meek shall inherit the land of Canaan," the meaning usually assigned by scholars to "land" in this context, but they shall inherit "the earth." Of course, there are suggestions in this of that "new heavens and a new earth" promised through the apostle Peter (2 Peter 3:13).
John Wesley’s Explanatory Notes
Verse 7
[7] Rest in the LORD, and wait patiently for him: fret not thyself because of him who prospereth in his way, because of the man who bringeth wicked devices to pass.
Rest — Do not repine at his dealings, but quietly submit to his will, and wait for his help.
Verse 8
[8] Cease from anger, and forsake wrath: fret not thyself in any wise to do evil.
Fret not — Either against the sinner for his success; or against God.
Do evil — If grief arise in thee, take care that it do not transport thee to sin.
Matthew Henry’s Concise Commentary
Commentary on Psalm 37:7-20
(Read Psalm 37:7-20)
Let us be satisfied that God will make all to work for good to us. Let us not discompose ourselves at what we see in this world. A fretful, discontented spirit is open to many temptations. For, in all respects, the little which is allotted to the righteous, is more comfortable and more profitable than the ill-gotten and abused riches of ungodly men. It comes from a hand of special love. God provides plentifully and well, not only for his working servants, but for his waiting servants. They have that which is better than wealth, peace of mind, peace with God, and then peace in God; that peace which the world cannot give, and which the world cannot have. God knows the believer's days. Not one day's work shall go unrewarded. Their time on earth is reckoned by days, which will soon be numbered; but heavenly happiness shall be for ever. This will be a real support to believers in evil times. Those that rest on the Rock of ages, have no reason to envy the wicked the support of their broken reeds.