He who disciplines the nations, does he not rebuke?
He who teaches man knowledge—
the LORD—knows the thoughts of man,
that they are but a breath.
Blessed is the man whom you discipline, O LORD,
and whom you teach out of your law,
to give him rest from days of trouble,
until a pit is dug for the wicked.
For the LORD will not forsake his people;
he will not abandon his heritage;
for justice will return to the righteous,
and all the upright in heart will follow it. —Psalm 94:10-15 ESV
Spurgeon, in The Treasury of David, comments on Psalm 94
Whether men admit or deny that God knows, one thing is here declared, namely, that The Lord knoweth the thoughts of man, that they are vanity. Not their words alone are heard, and their works seen, but he reads the secret motions of their minds, for men themselves are not hard to be discerned of him, before his glance they themselves are but vanity. It is in the Lord’s esteem no great matter to know the thoughts of such transparent pieces of vanity as mankind are, he sums them up in a moment as poor vain things. This is the sense of the original, but that given in the authorised version is also true—the thoughts, the best part, the most spiritual portion of man’s nature, even these are vanity itself, and nothing better. Poor man! And yet such a creature as this boasts, plays at monarch, tyrannises over his fellow worms, and defies his God! Madness is mingled with human vanity, like smoke with the fog, to make it fouler but not more substantial than it would have been alone. How foolish are those who think that God does not know their actions, when the truth is that their vain thoughts are all perceived by him! How absurd to make nothing of God when in fact we ourselves are as nothing in his sight.