6 His face turned pale and he was so frightened that his legs became weak and his knees were knocking.

Read Daniel 5:6 Using Other Translations

Then the king's countenance was changed, and his thoughts troubled him, so that the joints of his loins were loosed, and his knees smote one against another.
Then the king's color changed, and his thoughts alarmed him; his limbs gave way, and his knees knocked together.
and his face turned pale with fright. His knees knocked together in fear and his legs gave way beneath him.