Another interpretation: "For he will not pardon your transgression" (Exodus 23:21). Why? Because he is a messenger, and whatever the messenger is commanded to do, he does; but I lift up the countenance to you, as it is said, "May the LORD lift up His countenance toward you" (Numbers 6:26). David said: Master of the universe, are You handing us over to an angel who does not lift up the countenance? Who could stand before him? "If You, LORD, should mark iniquities" etc. (Psalms 130:3). And lest you say that forgiveness is not with You, it is with You; this is what is written, "For with You is forgiveness, that You may be feared" (Psalms 130:4). "For My name is within him" (Exodus 23:21): the name of the Holy One, blessed be He, is shared with each and every angel. Moses said to Him: I do not ask that an angel go with us, "If Your Presence does not go" etc. (Exodus 33:15); if You do not go with us, we will not stir from our place. The Holy One, blessed be He, said: By your life, I will not even send an angel before you; rather I will send the hornet before you, as it is said, "And I will send the hornet" (Exodus 23:28). How did the Amorites die? Rabbi Levi said: He would pair two hornets to each one, and each would pour its venom into his eyes, and he would die at once. Rabbi Hiyya bar Abba said: How did they die? A churning entered them, and they had violent diarrhea, and they died. Rabbi Berekhiah said: The Holy One, blessed be He, would bind them before Israel, and Israel would come and kill them, as it is said, "And the LORD our God delivered them into our hand" (Deuteronomy 3:3), like a man who binds his enemy before his son. And lest you say the Amorites were small, the Holy One, blessed be He, praises them: "whose height was like the height of cedars" (Amos 2:9); and what did I do to them? "I destroyed his fruit above" etc. (Amos 2:9), this is their heavenly prince, "and his roots beneath" (Amos 2:9), these are the Amorites. The Holy One, blessed be He, said: In this world I sent an angel before them, and it cut off the nations of the world; but in the world to come I will send you Elijah, may he be remembered for good, as it is said, "Behold, I am sending you Elijah the prophet before the coming of the great and awesome day of the LORD" (Malachi 3:23). From where does that saying of folk come, "When we were young, we were treated as men; now that we are old, we are treated as children"? For at first it is written, "And the LORD went before them by day" (Exodus 13:21), and at the end it is written, "Behold, I am sending an angel before you" (Exodus 23:20). A certain heretic said to Rav Idi: It is written, "And to Moses He said: Come up to the LORD" (Exodus 24:1); it should have said "Come up to Me." He said to him: This is Metatron, whose name is like the name of his Master, as it is written, "For My name is within him." If so, let us worship him! It is written, "Do not rebel against him" [do not exchange Me for him]. If so, why "he will not pardon your transgression"? He said to him: We hold by tradition that we did not accept him even as a guide-messenger, as it is written, "And he said to Him: If Your Presence does not go, do not bring us up from here" (Exodus 33:15).
No Angel Will Go but the Presence Itself, the Hornet, and Metatron
Yalkut Shimoni on Torah 359:8
דָּבָר אַחֵר. כִּי לֹא יִשָּׂא לְפִשְׁעֲכֶם. לָמָּה. שֶׁהוּא שָׁלִיחַ, וְכָל מַה שֶּׁהַשָּׁלִיחַ מְצֻוֶּה לַעֲשׂוֹת, הוּא עוֹשֶׂה, אֲבָל אֲנִי נוֹשֵׂא לָכֶם פָּנִים, שֶׁנֶּאֱמַר (במדבר ו, כו) "יִשָּׂא ה' פָּנָיו". אָמַר דָּוִד. רִבּוֹנוֹ שֶׁל עוֹלָם, וּלְמַלְאָךְ אַתָּה מוֹסְרֵנִי, שֶׁאֵינוֹ נוֹשֵׂא פָנִים, מִי יוּכַל לַעֲמֹד בּוֹ, (תהלים קל, ג) "אִם עֲוֹנוֹת תִּשְׁמָר יָהּ" וְגוֹ'. אִם תֹּאמַר שֶׁהַסְּלִיחָה אֵינָהּ עִמְּךָ, עִמְּךָ הִיא, הָדָא הוּא דִּכְתִיב "כִּי עִמְּךָ הַסְּלִיחָה לְמַעַן תִּוָּרֵא". כִּי שְׁמִי בְּקִרְבּוֹ. שְׁמוֹ שֶׁל הַקָּדוֹשׁ בָּרוּךְ הוּא מְשֻׁתָּף עִם כָּל מַלְאָךְ וּמַלְאָךְ. אֲמַר לֵיהּ מֹשֶׁה. אֵינִי מְבַקֵּשׁ שֶׁיֵּלֵךְ מַלְאָךְ עִמָּנוּ, (שמות לג, טו) "אִם אֵין פָּנֶיךָ הֹלְכִים" וְגוֹ', אִם אֵין אַתָּה מְהַלֵּךְ עִמָּנוּ אֵין אָנוּ זָזִין מִמְּקוֹמֵנוּ. אֲמַר הַקָּדוֹשׁ בָּרוּךְ הוּא. חַיֶּיךָ, אֲפִלּוּ מַלְאָךְ לֹא אֶשְׁלַח לְפָנֶיךָ, אֶלָּא הַצִּרְעָה אֶשְׁלַח לְפָנֶיךָ, שֶׁנֶּאֱמַר "וְשָׁלַחְתִּי אֶת הַצִּרְעָה". כֵּיצַד הָיוּ הָאֱמוֹרִיִּים מֵתִים. אֲמַר רַבִּי לֵוִי. שְׁתֵּי צְרָעוֹת הָיָה מְזַוֵּג לְכָל אֶחָד וְאֶחָד, כָּל אַחַת וְאַחַת הָיְתָה שׁוֹפֶכֶת אַרְסָהּ בְּתוֹךְ עֵינָיו וּמִיָּד הָיָה מֵת. רַבִּי חִיָּא בַּר אַבָּא אֲמַר. כֵּיצַד הָיוּ מֵתִים. חִלְחוּל הָיָה נִכְנָס בָּהֶן, וְהָיוּ מַתְרִיזִין, וְהָיוּ מֵתִין. רַבִּי בֶּרֶכְיָה אֲמַר. הַקָּדוֹשׁ בָּרוּךְ הוּא הָיָה אוֹסְרָן לִפְנֵי יִשְׂרָאֵל, וְהָיוּ בָאִין וְהוֹרְגִין אוֹתָן, שֶׁנֶּאֱמַר (דברים ג, ג) "וַיִּתֵּן ה' אֱלֹהֵינוּ בְּיָדֵנוּ", כְּאָדָם שֶׁאוֹסֵר שׂוֹנְאוֹ לִפְנֵי בְנוֹ. אִם תֹּאמַר קְטַנִּים הָיוּ הָאֱמוֹרִיִּים. הַקָּדוֹשׁ בָּרוּךְ הוּא מְשַׁבְּחָם (עמוס ב, ט) "אֲשֶׁר כְּגֹבַהּ אֲרָזִים גָּבְהוֹ", וּמַה הָיִיתִי עוֹשֶׂה לָהֶם, "וָאַשְׁמִיד פִּרְיוֹ מִמַּעַל" וְגוֹ', זֶה הַשָּׂר שֶׁלָּהֶן, (שם) "וְשָׁרָשָׁיו מִתָּחַת", אֵלּוּ הָאֱמוֹרִיִּים. אָמַר הַקָּדוֹשׁ בָּרוּךְ הוּא. בָּעוֹלָם הַזֶּה שָׁלַחְתִּי לִפְנֵיהֶם מַלְאָךְ, וְהָיָה מַכְרִית אֻמּוֹת הָעוֹלָם, אֲבָל לָעוֹלָם הַבָּא אֵלִיָּהוּ זָכוּר לַטּוֹב אֶשְׁלַח לָכֶם, שֶׁנֶּאֱמַר (מלאכי ג, כג) (הִנְּנִי) ["הִנֵּה אָנֹכִי] שֹׁלֵחַ לָכֶם אֶת אֵלִיָּה הַנָּבִיא לִפְנֵי בּוֹא יוֹם ה' הַגָּדוֹל וְהַנּוֹרָא". מִנָּא הָא מִלְּתָא דְּאָמְרֵי אִינְשֵׁי, כִּי הֲוִינָן זוּטָרֵי, לְגַבְרֵי, הַשְׁתָּא דְקָשִׁישְׁנָא, לְדַרְדָּקֵי. דִּכְתִיב מֵעִיקָרָא "וַה' הֹלֵךְ לִפְנֵיהֶם יוֹמָם", וּלְבַסּוֹף כְּתִיב הִנֵּה אָנֹכִי שֹׁלֵחַ מַלְאָךְ לְפָנֶיךָ. אַמֲר לֵיהּ הַהוּא אֶפִּיקוֹרוֹס לְרַב אֵידִי. כְּתִיב (שמות כד, א) "וְאֶל מֹשֶׁה אָמַר עֲלֵה אֶל ה'", "עֲלֵה אֵלַי" מִבַּעְיָא לֵיהּ. אֲמַר לֵיהּ. זֶה מְטַטְרוֹן, שֶׁשְּׁמוֹ כְּשֵׁם רַבּוֹ, דִּכְתִיב כִּי שְׁמִי בְּקִרְבּוֹ. אִי הָכִי. נִפְלְחוּ לֵיהּ. כְּתִיב אַל תַּמֵּר בּוֹ, אַל תְּמִירֵנִי בּוֹ. אִם כֵּן, לֹא יִשָּׂא לְפִשְׁעֲכֶם לָמָּה לִי. אֲמַר לֵיהּ. הֵימָנוּתָא בְּיָדוֹ דַּאֲפִלּוּ בְּפַרְוַונְקָא נַמֵּי לָא קַבִּילְנֵיהּ, דִּכְתִיב "וַיֹּאמֶר אֵלָיו אִם אֵין פָּנֶיךָ הֹלְכִים אַל תַּעֲלֵנוּ מִזֶּה".