Charles Ellicott Commentary Job 40:23

"Behold, if a river overflow, he trembleth not; He is confident, though a Jordan swell even to his mouth." — Job 40:23 (ASV)

Behold, he drinks up a river. —This verse is better rendered, Behold, if a river overflow (or, is violent), he trembles not (or, hastens not); he is confident, though Jordan swell up to his mouth.