Let me not be ashamed, O LORD; for I have called upon thee: let the wicked be ashamed, and let them be silent in the grave.
Let me ... O Lord; for I have called upon thee - resuming the prayer (Psalms 31:1) in a reverse order of the clauses; the 'calling upon' Yahweh here is the outward expression of the "trust" there.
Let the wicked ... grave - Hebrew, Shª'owl (H7585), the unseen world. The wicked, who call not upon God, shall, in just retribution, be consigned to the silent grave, wherein they can no longer call upon Him. Not the righteous, who call upon Him, but the wicked, who do not (Psalms 53:4), shall be ashamed. They now "slander" noisily; but soon that shall be put out of their power, in the 'noiseless region of the dead' (cf. next verse).