"And He said, I am the God of your father" (Exodus 3:6): He revealed Himself to him in the voice of his father Amram, so that he would not be afraid. At that moment Moses rejoiced and said, "My father Amram!" The Holy One, blessed be He, said to him: "You said that I am your father, but I am only the God of your father." At that moment Moses hid his face. The Holy One, blessed be He, said to him: "You showed Me honor; by your life, I will show you honor," as it is said (Exodus 34:30), "And Aaron and all the children of Israel saw Moses" and his face shone. You feared, for he was afraid to look; therefore "they were afraid to approach him." As a reward for fearing to look, "he beholds the likeness of the Lord" (Numbers 12:8). It is written (Exodus 33:20), "And He said, You cannot see My face." The Holy One, blessed be He, said to Moses: "When I wished it, you did not wish; and now that you wish it, I do not wish." But Rabbi Shmuel bar Nachmani disagrees, saying in the name of Rabbi Yonatan: as a reward for three things he merited three things. As a reward for "and Moses hid his face," he merited the radiance of his face. As a reward for "because he was afraid" and so on, and so forth.
God Spoke in His Father's Voice So Moses Would Not Fear
Yalkut Shimoni on Torah 171:1
(שמות ג ו) וַיֹּאמֶר אָנֹכִי אֱלֹהֵי אָבִיךָ, נִגְלָה עָלָיו בְּקוֹלוֹ שֶׁל עַמְרָם אָבִיו, כְּדֵי שֶׁלֹּא יִתְיָרֵא. בְּאוֹתָהּ שָׁעָה שָׂמַח מֹשֶׁה וְאָמַר, עַמְרָם אָבִי. אָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא, אַתָּה אָמַרְתָּ שֶׁאֲנִי אָבִיךָ וְאֵינִי אֶלָּא אֱלֹהֵי אָבִיךָ. בְּאוֹתָהּ שָׁעָה וַיַּסְתֵּר מֹשֶׁה (אֶת) פָּנָיו. אָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא, חָלַקְתָּ לִי כָּבוֹד, חַיֶּיךָ אֲנִי חוֹלֵק לְךָ כָּבוֹד, שֶׁנֶּאֱמַר (שמות לד, ל) "וַיַּרְא אַהֲרֹן וְכָל בְּנֵי יִשְׂרָאֵל אֶת מֹשֶׁה" וְגוֹ'. אַתָּה יָרֵאתָ כִּי יָרֵא מֵהַבִּיט, לְפִיכָךְ "וַיִּירְאוּ מִגֶּשֶׁת אֵלָיו". בִּשְׂכַר מֵהַבִּיט, (במדבר יב, ח) "וּתְמוּנַת ה' יַבִּיט". כְּתִיב (שמות ג, כ) "וַיֹּאמֶר לֹא תּוּכַל לִרְאוֹת אֶת פָּנָי", אָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא לְמֹשֶׁה, כְּשֶׁרָצִיתִי לֹא רָצִיתָ, וְעַכְשָׁיו שֶׁאַתָּה רוֹצֶה, אֵינִי רוֹצֶה. וּפְלִיגָא דְּרַבִּי שְׁמוּאֵל בַּר נַחְמֵנִי אָמַר רַבִּי יוֹנָתָן, דְּאָמַר, בִּשְׂכַר שָׁלֹשׁ זָכָה לְשָׁלֹשׁ. בִּשְׂכַר וַיַּסְתֵּר מֹשֶׁה פָּנָיו, זָכָה לִקְלַסְתֵּר פָּנִים. בִּשְׂכַר כִּי יָרֵא וְגוֹ' וְכוּ'.