He confirms the last sentence, that such should be the trembling, that those who were oppressed with all kinds of evil, dare not utter their complaints freely. He says, all hands should be loosened, and all knees should be unstable as water We know that this doctrine frequently occurs with the Prophets, by which God shows that men's hearts were in his hands. But since profane men are fierce against God, through trusting in their own wealth or fortitude, hence, on the contrary, God pronounces that they should be timorous and anxious, nay, almost vanishing away, and as it were lifeless, as if their knees were flowing away amidst water, and their hands were relaxed. It follows --

All knees shall be weak as water - Calmet understands this curiously: La frayeur dont on sera saisi, fera qu'on ne pourra retenir son urine. D'autres l'expliquent d'une autre souillure plus honteuse. I believe him to be nearly about right. St. Jerome is exactly the same: Pavoris magnitudine, urina polluet genua, nec valebit profluentes aquas vesica prohibere. This and other malretentions are often the natural effect of extreme fear or terror.

All hands shall be feeble,.... No strength in them, to lay hold on weapons of war to defend themselves, or fight the enemy; no heart nor courage in them, to go forth and meet him; and even afraid to lift up their voice in mourning, lest they should be heard, and pursued, and taken:
and all knees shall be weak as water; tremble and beat one against another, for fear of the enemy; or,
"shall flow with water,''
as the Targum; either with sweat or urine, which are sometimes both caused by fear.

shall be weak as water--literally, "shall go (as) waters"; incapable of resistance (Joshua 7:5; Psalm 22:14; Isaiah 13:7).