O love Jehovah, all ye his meek ones! In my opinion, the Psalmist does not here exhort the saints to fear and reverence God, as many think, but encourages them to confide in him; or, in other words, to devote themselves wholly to him, to put all their hope in him, and to rely entirely upon him, without seeking to any other. Whence is it that our own fond devices delight us, but because we do not delight in God so much as we ought, and because our affections do not cleave to him? This love of God, therefore, comprehends in it all the desires of the heart. By nature, all men greatly desire to be in a prosperous or happy state; but while the greater number are fascinated by the allurements of the world, and prefer its lies and impostures, scarcely one in a hundred sets his heart on God. The reason which immediately follows confirms this interpretation; for the inspired Psalmist exhorts the meek to love God, because he preserves the faithful, which is as if he had desired them to rest satisfied with his guardianship, and to acknowledge that in it they had sufficient succor. In the meantime, he admonishes them to keep a good conscience, and to cultivate uprightness, since God promises to preserve only such as are upright and faithful. On the other hand, he declares that he plentifully recompenses the proud, in order that when we observe them succeeding prosperously for a time, an unworthy emulation may not entice us to imitate them, and that their haughtiness, and the outrage they commit, while they think they are at liberty to do what they please, may not crush and break our spirits. The amount of the whole is this, Although the ungodly flatter themselves, while they proceed in their wickedness with impunity, and believers are harassed with many fears and dangers, yet devote yourselves to God, and rely upon his grace, for he will always defend the faithful, and reward the proud as they deserve. Concerning the meaning of the Hebrew word l-ytr, al-yether, which we have rendered plentifully, [1] interpreters are not agreed. Some translate it pride, meaning that to those who behave themselves proudly, God will render according to their pride; others translate it to overflowing, or beyond measure, because ytr, yether, signifies in Hebrew residue or remnant; instead of which I have translated it plentifully. Some understand it as extending to their children and children's children, who shall remain the residue of their seed. Besides, as the same word is frequently used for excellence, [2] I have no doubt that the prophet elegantly rebukes the proud, who imagine that their fancied excellence is not only a shield to them, but, an invincible fortress against God. As their groundless authority and power blind, or rather bewitch them, so that they vaunt themselves intemperately and without measure against those who are lowly and feeble, the prophet elegantly says that there is a reward in store for them proportioned to the haughtiness with which they are puffed up.

Footnotes

1 - Literally, "with plenty."

2 - The word g'h, gaäh, from which g'vh, gaävah, which we have rendered proudly, is derived, signifies elatus est, eminuit; and g'vh, gaävah, "is sometimes taken in a bad sense for pride or arrogance, as in Psalm 10:2; and sometimes in a good sense for splendor, magnificence, strength, excellence. In the latter sense it is used of God, Psalm 68:34, His height, or excellence and strength, are in the clouds." -- Hammond.

O love the Lord, all ye his saints - This is the "application" of all the truths suggested in the psalm. The experience of the psalmist had shown the wisdom of trusting in God in times of danger and trouble, and had laid the foundation for a proper exhortation to others to imitate his example; an argument why all the people of God should love him, and should be of good courage. The reason here assigned for their loving the Lord is, that he preserves those who are faithful to him, and "rewards the proud doer." This is a reason for loving God, or for putting our trust in him, though the psalmist does not say that this is the only reason for doing it. The meaning here is, that the dealings of God toward the psalmist had established this truth in regard to the character of God, that he does preserve the faithful, and does punish the proud, and that this fact constitutes a reason why all his people should confide in him.
For the Lord preserveth the faithful - The faithful; those who put their trust in him; those who do not give up in despondency and despair in time of danger and trouble; those who do not forsake him even though for a time he seems to forsake them. What God looks for mainly in his people is confidence; faithfulness; trust; fidelity.
And plentifully rewardeth - "Abundantly" rewards. Literally, "in plenty." That is, his punishment does not fall short of the desert of the wicked man. It is ample or full. He does full justice.
The proud doer - "The man working pride." The reference is to the man who is confident in himself; who seeks to aggrandize himself, and who in doing this is regardless of the rights of others.

O love the Lord, all ye his saints - It is only the saints that can love God, as they only are made partakers of the Divine nature. Holy spirits can love God, who is the fountain of their holiness; and the saints should love him.
Preserveth the faithful - Those who, being filled with the love of God, bring forth the fruits of that love - universal obedience to the will of God; for to such persons his commands are not grievous, their duty is their delight; while a man is faithful to the grace he has received, that is, uses and improves the talents with which God has intrusted him, God's service is perfect freedom.
The proud doer - The man of the proud heart, haughty and supercilious carriage, and insulting and outrageous conduct. A proud man is peculiarly odious in the sight of God; and in the sight of reason how absurd! A sinner, a fallen spirit, an heir of wretchedness and corruption-proud!
Proud of what? Of an indwelling devil! Well; such persons shall be plentifully rewarded. They shall get their due, their whole due, and nothing but their due.

O love the Lord, all ye his saints,.... To whom his goodness extends; who are favoured with the blessings of his grace, as pardon, peace, and righteousness; and who particularly are sanctified by his Spirit, and have principles of grace and holiness wrought in their hearts: these, even all of them, are called upon to love the Lord, having that grace implanted in their souls; that is, to express it, not by words, but by deeds, under a sense of the love and kindness of God to them; and to join with the psalmist in an affectionate reverence of him, trust in him, and thankfulness to him, on account of his marvellous kindness showed him;
for the Lord preserveth the faithful; such as trust in him, believe in Christ, and are faithful to his word and ordinances, abide by them, and stays near his people; these he not only preserves in a providential way, but he preserves them in a way of special grace; he keeps them "from evil", as the Targum; from the evil of sin; from a total and final falling away by it; from the evil of the world, so as not to be drawn off from Christ and his ways, either by its frowns or flatteries; and from the evil one, Satan, from being destroyed by him and his temptations; and these are preserved safe to the kingdom and glory of Christ, by the mighty power of God: some render the words, "the Lord keepeth faithfulness" (i); he will never suffer his own faithfulness to fail; he is a covenant keeping God, and is always true to his word and promise;
and plentifully rewardeth the proud doer; such as all self-righteous persons are, and all that speak grievous things proudly and contemptuously against the truly righteous, Psalm 31:18; who bear hard upon them, and oppress them; and such as antichrist and his party, who exalts himself above all that is called God; but in what those deal proudly, God is above them, an more than a match for them, and he sets himself against them; he resists them, and will reward them according to their works.
(i) "fidelitatem", Gejerus; or "fidelitles", Ainsworth.

the Lord . . . proud doer--literally, "the Lord is keeping faith," that is, with His people, and is repaying, &c. Then let none despair, but take courage; their hopes shall not be in vain.