The wicked shall see it, and be grieved; he shall gnash with his teeth, and melt away: the desire of the wicked shall perish. The wicked shall see it - רשע rasha, the wicked one. Some think Satan is meant. It is distinguished from רשעים reshaim, wicked men, in the conclusion of the verse.
Shall gnash with his teeth - Through spite and ill will.
And melt away - Through envy and hopeless expectation of similar good; for his desire in reference to himself and in reference to him who is the object of his envy, shall perish - shall come to nothing.
Commentary on the Bible, by Adam Clarke [1831].