זוהר שמות — דף קפא ע”א

The third secret is the letter Vav. This letter is the figure of the secret of Man, standing upon twelve chariots (Merkavot), which become twenty-four when they separate. The body encompasses twenty-four: six for the head, eighteen for the body. When the fullness of this letter appears, all negative sides are blocked and separated from the Moon. The letter Vav is the light that illuminates the Shekhinah, and its secret is inscribed in all configurations of its form.