Albert Barnes Commentary Proverbs 25:26

"[As] a troubled fountain, and a corrupted spring, [So is] a righteous man that giveth way before the wicked." — Proverbs 25:26 (ASV)

Falling down before – that is, yielding and cringing. To see this instead of steadfastness is as grievous as for the traveler to find the spring, at which he hoped to quench his thirst, muddy and defiled.