Psalms 63:11

But the king The connexion is unintelligible unless the king is identified with the Psalmist, whose enemies are destroyed. Cp. Psalms 61:6 ff.

that sweareth by him Grammatically -him" may refer to the king or to God, but usage decides that God is meant. Cp. Deuteronomy 6:13; Deuteronomy 10:20; Isaiah 65:16. Those who invoke His Name as the attestation of their oaths are His loyal worshippers; they share the triumph of the king who is His representative.

but the mouth&c. For the mouth &c. Those who -speak lies" are those who rebel against God and His king, deluding men by false promises to join an undertaking which is false in its principle and aim. See Psalms 4:2, note; Psalms 62:4. They are all completely silenced.

Cp. the similar ending of Psalms 64. St Paul may have had the phrase in mind in Romans 3:19. The context shews how familiar the Psalms were to him.