'Knees' in the Bible

All hands shall be feeble, and all knees shall be weak as water.

It shall be, when they tell you, Why do you sigh? that you shall say, Because of the news, for it comes; and every heart shall melt, and all hands shall be feeble, and every spirit shall faint, and all knees shall be weak as water: behold, it comes, and it shall be done, says the Lord Yahweh.

Again he measured one thousand, and caused me to pass through the waters, waters that were to the knees. Again he measured one thousand, and caused me to pass through [the waters], waters that were to the waist.