זוהר שמות — דף קיט ע”ב

Your spirit comes from the side of the central pillar, the vav, which contains father and mother (yod-heh). Your lower soul comes from the side of the letter heh — the lower Shekhinah does not leave you. Just as father and mother guard the son, so they guard the daughter. Each night the spirit ascends in the supernal mind and receives a crown. The arm tefillin contain 14 letters of the full Name — the hand of the Shekhinah. Into your hand I entrust my spirit: the spirit is deposited in the protecting hand.