זוהר שמות — דף קסב ע”א

YHWH is Elohim — the principle of all: this name above and this name below, the secret of the upper world and the lower world. All commandments of the Torah are included in Zakhor (remember) and Shamor (guard), and all is one. The evening prayer is obligatory because the evening Shema is obligatory, and the Holy One unifies at night as during the day. The three names of the Shema correspond to the four sections of the head-tefillin: the first YHWH is the supernal point, Eloheinu is the world to come, and the last YHWH is the synthesis of right and left together in the head-tefillin. Barukh shem kavod is the secret of the arm-tefillin, the synthesis of all.