Charles H. Spurgeon on Psalms 59:7

Behold, they belch out with their mouth, etc. Bark like dogs, so Aben Ezra; or, bubble out, as a fountain bubbles out with water; so they cast out their wickedness in great abundance (see Jer 6:7); the phrase denotes the abundance of evil things and wicked speeches that come out of their mouths, which showed the naughtiness of their hearts; so David's enemies blustered and threatened what they would do to him could they find him; and Christ's enemies poured out their wicked charges of blasphemy and sedition against him in great plenty, and without proof. John Gill.