'Knees' in the Bible

Then he sent a third captain of fifty with his fifty men; and the third captain of fifty went up, and falling on his knees before Elijah, requesting mercy of him, said, O man of God, let my life and the life of these your fifty servants be of value to you.

And he took him in to his mother, and she took him on her knees and kept him there till the middle of the day, when his life went from him.