Albert Barnes Commentary Psalms 124:5

"Then the proud waters had gone over our soul." — Psalms 124:5 (ASV)

Then the proud waters had gone over our soul—Over us. The word 'proud' here is applied to the waters as if raging, swelling, rolling, tumultuous; as if they were self-confident, arrogant, haughty.

Such raging billows, as they break and dash upon the shore, are a striking emblem of human passions, whether in an individual, or in a gathering of men—as an army or a mob. .

This is again an amplification, or an ascent of thought. (See the notes at Psalms 124:2). It is, however, nothing more than a poetical embellishment, adding intensity to the expression.