Parashas Shemos
וַיֹּ֗אמֶר אָנֹכִי֙ אֱלֹהֵ֣י אָבִ֔יךָ אֱלֹהֵ֧י אַבְרָהָ֛ם אֱלֹהֵ֥י יִצְחָ֖ק וֵאלֹהֵ֣י יַעֲקֹ֑ב וַיַּסְתֵּ֤ר מֹשֶׁה֙ פָּנָ֔יו כִּ֣י יָרֵ֔א מֵהַבִּ֖יט אֶל־הָאֱלֹהִֽים׃
and continued, “I am the God of your fatherdyour father Including his household.—the God of Abraham, the God of Isaac, and the God of Jacob.” And Moses hid his face, for he was afraid to look at God.eGod Or “a divine being.”
Torah Temimah points to R’ Shmuel bar Nachmani in the name of R’ Yonasan — Berachos 7a (verified).
ויסתר משה פניו — א״ר שמואל בר נחמני א״ר יונתן: בשכר שלש זכה לשלש; בשכר ויסתר משה פניו זכה לקלסתר פנים.
English: “And Moshe hid his face” — R’ Shmuel bar Nachmani said in the name of R’ Yonasan: In the merit of three [acts] he merited three [rewards]; in the merit of “and Moshe hid his face” he merited a radiant countenance.
Custom
Chazal teach that Moshe’s covering of his face at the bush was rewarded with the luminous face he later received.