slow to anger, and great in power - that is, but great in power, so as to be able in a moment, if He pleases, to destroy the wicked. His long-suffering is not from want of power to punish (Exo 34:6, Exo 34:7).
not at all acquit - literally, “will not acquitting acquit,” or treat as innocent.
Lord hath his way in the whirlwind - From this to Nah 1:5, inclusive, is a description of His power exhibited in the phenomena of nature, especially when He is wroth. His vengeance shall sweep away the Assyrian foe like a whirlwind (Pro 10:25).
clouds are the dust of his feet - Large as they are, He treads on them, as a man would on the small dust; He is Lord of the clouds, and uses them as He pleases.