ייִדישער מחשבֿה אויף שמות 34:35

Shemot Rabbah 80, asks "whence did Moses get the "rays of glory" that illuminated his face and emitted rays? The Rabbis answer that he got them from the "cave," since it states "when you are in the hollow of the rock, when My glory passes by, I will place you there." (Exodus 33,22-23) Rabbi Berechiyah said that the tablets were six tefachim long and wide. G-d supported two, (tefachim=handsbreadths) Moses supported two, whereas the other two were in the center. This is the origin of the "rays of glory." Rabbi Yehudah bar Nachmayni says "G-d wrote with a pen, and a little of the ink that was left over touched Moses’s face, and that is where "the rays of glory" came from and this is why the Torah says "he did not know that his face emitted rays of light." (34,35)