"Then We inspired to Moses, 'Strike with your staff the sea.'" Gabriel came to him on a horse and commanded him to strike the sea with his staff; so he struck it. "And it parted," the sea, "and each portion was like a great mountain." The "tawd" (mountain) is the mountain.
Qatadah said: It became twelve paths, a path for each tribe, and what was between every two paths became like arches, with some of them seeing others.