Psalms 4:6

There be many that say, &c.— There be many (the multitude, the generality of men, in almost every station) that say, who will shew us any good? i.e. "Who will heap honours upon us? Who will point out the way to wealth and luxury? Who will present new scenes of pleasure, that we may indulge our appetites, and give full scope to the rovings of a wanton fancy?" That this is the substance of what was intended by the sacred writer in this question, the words put in opposition to it, in which he expresses his own wiser sentiments, are an undeniable proof; Lord, lift thou up the light of thy countenance upon us. That what he here suggests is a fair representation of fact, experience loudly testifies; and that it is a false notion of human happiness, and a fatal error, reason plainly teaches; for what are honours, what are riches, what is sensual pleasure? They are light as vanity, fleeting as a bubble, thin and unsubstantial as air. The favour of God and his approbation is absolutely necessary to the happiness of mankind. The displeasure of our Maker includes in it the utmost distress and infamy; and his favour, every thing great, good, and honourable: so that the devout prayer of the Psalmist will be likewise the fervent and humble supplication of every wise and holy mind; Lord, lift thou up, &c. See Foster's Serm. vol. 4:

Lord, lift thou up the light of thy countenance— For the understanding of this and several other passages in the Psalms, it must be remembered, that when Moses had prepared the ark, in which he deposited the tables of the covenant, the glory of the Lord filled the tabernacle; and after this, wherever the ark rested, God always manifested his peculiar presence among his people, by a glorious visible appearance upon the mercy-seat; and this continued as long as Solomon's temple lasted. It is this which is always alluded to where mention is made in the Psalms of the light of God's countenance, or his making his face to shine. Now as this was a standing miraculous testimony of God's peculiar providence over the Jews; so those expressions of his making his face to shine, his lifting up the light of his countenance, and the like, did in common use signify his being gracious unto them, and taking them under his immediate protection. They are used in this sense, Numbers 11:25. In like manner, the hiding of God's face meant the withdrawing of his favour and protection from them.