Psalms 62:9 - Joseph Benson’s Commentary on the Old and New Testaments

Surely men of low degree are vanity Are most vain, impotent, and helpless creatures in themselves. This he delivers as a reason, or argument, to enforce his foregoing exhortation to trust in God, because there was no other person or thing to which they could safely trust. Men of high degree are a lie That is, deceitful; because unable to perform what by their power and dignity they seem to promise. They raise men's expectations, and afterward disappoint them, and so deceive those that trust in them. In which sense lying is ascribed to a fountain, Jeremiah 15:18; to wine, Hosea 9:2; and to the olive, Hebrews 3:17, (see the Hebrew,) when they do not give what they promise. Or, a lie may signify, a mere nothing; for a lie has no reality in it.