We read in Parashat Ki-Tisa of the mysterious exchange between Moshe and the Almighty in the aftermath of the sin of the golden calf, during which Moshe asks God to show him His “glory” (“har’eini na et kevodekha” – 33:18). God responds that no man is capable of beholding His “face,” but He would instead show Moshe His “back” (33:20-23). Rashi, based on the Gemara (Berakhot 7a), explains that God showed Moshe the “kesher shel tefillin,” the knot of the Almighty’s tefillin. The knot of the tefillin shel rosh is positioned in the back of the neck, and this is what the Torah means when it says that Moshe was shown the Almighty’s “back.”
Rav Mordechai Yosef Leiner of Izhbitz, in his Mei Ha-shiloach, offers a symbolic explanation of the Gemara’s interpretation of the verses. Tefillin, which we bind upon our bodies, symbolizes the unbreakable bond between us and the Almighty. The Gemara earlier )Berakhot 6a) comments that God’s tefillin contains words of praise for Benei Yisrael, and the Mei Ha-shiloach explains that God gives us praise for our unconditional and unshakable connection to Him, symbolized by the tefillin. Just as we wear tefillin to express our unwavering love and devotion to God, He, too, remains unconditionally bound and devoted to us, and thus He, too, wears “tefillin,” so-to-speak. In the aftermath of the sin of the golden calf, after Benei Yisrael committed the most grievous of all sins, bowing to and worshipping a graven image, God showed Moshe the “kesher shel tefillin.” He indicated to Moshe that despite His angry response to the golden calf, He nevertheless remains eternally and unreservedly connected and devoted to His beloved nation.
This might be the significance of God’s hiding His “face” from Moshe during this prophetic vision, while showing him His “back.” Just as we cannot discern much about a person’s appearance from the back, as it is primarily the face that lends a person his unique, distinctive appearance, similarly, there is far more about God that we cannot see and understand than what we can see and understand. God’s “face,” His true characteristics, will always remain hidden, even from Moshe Rabbenu. What He does show us, however, is the “kesher shel tefillin,” His unshakable love and commitment to Am Yisrael. We are assured that even in times of failure and spiritual collapse, the bond between us remains intact, and this is the aspect of God’s being that we are shown and that we need to recognize.