They asked Rabban Yochanan ben Zakkai: Why were the first tablets the work of Heaven and the second the work of man? He said to them: I will tell you to what the matter is comparable. To a king who married a wife, and the paper and the scribe were his, he crowned her at his own expense and brought her into his house. The king saw her laughing with one of his servants, grew angry with her, and put her out. Her best man came to him and said: My lord, do you not know from where you took her? Was she not raised among the servants, and since she grew up among them her heart is bold with them? The king said to him: And what do you ask, that I be reconciled to her? Bring paper and a scribe of your own, and here is my own handwriting. So too Moses said to the Holy One, blessed be He, when Israel did that deed: Do You not know from what place You brought them out, from a place of idolatry? The Holy One, blessed be He, said to him: And what do you ask, that I be reconciled to them? Bring the tablets of your own, and here is My handwriting. The Holy One, blessed be He, said to him: By your life, just as you gave your soul for them in this world, so too in the time to come, when I bring them Elijah, may he be remembered for good, the two of you will come as one, as it is said, "The LORD, His way is in the whirlwind and in the storm" (Nahum 1:3). "In the whirlwind" (basufah), this is Moses, as it is written, "and she placed it among the reeds (basuf) by the bank of the river" (Exodus 2:3); "and in the storm" (uvis'arah), this is Elijah, as it is written, "and Elijah went up by a whirlwind into heaven" (II Kings 2:11). At that hour he comes and comforts you, as it is said, "Behold, I send you Elijah the prophet... and he shall turn the heart of the fathers to the children" (Malachi 3:23-24). (It is written in the hint section.)
First Tablets the Work of Heaven, Second Tablets the Work of Hands
Yalkut Shimoni on Torah 397:1
שָׁאֲלוּ אֶת רַבָּן יוֹחָנָן בֶּן זַכַּאי. מִפְּנֵי מָה לוּחוֹת הָרִאשׁוֹנוֹת מַעֲשֵׂה שָׁמַיִם וְהַשְּׁנִיּוֹת מַעֲשֵׂה אָדָם. אָמַר לוֹ. אוֹמַר לָכֶם לְמָה הַדָּבָר דּוֹמֶה לְמֶלֶךְ שֶׁנָּשָׂא אִשָּׁה, וְהַנְּיָר וְהַלַּבְלָר מִשֶּׁלּוֹ, עִטְרָהּ מִשֶּׁלּוֹ וְהִכְנִיסָהּ לְתוֹךְ בֵּיתוֹ. רָאָה אוֹתָהּ הַמֶּלֶךְ שׂוֹחֶקֶת עִם עֶבֶד אֶחָד מִשֶּׁלּוֹ, קָצַף עָלֶיהָ וְהוֹצִיאָהּ. בָּא שׁוֹשְׁבִינָהּ אֶצְלוֹ. אָמַר לוֹ. מָרִי, אֵין אַתָּה יוֹדֵעַ מֵהֵיכָן נָטַלְתָּ אוֹתָהּ, לֹא מִבֵּין הָעֲבָדִים גִּדּוּלָהּ, וְכֵיוָן שֶׁגָּדְלָה בֵּינֵיהֶן לִבָּהּ גַּס בָּהֶן. אָמַר לוֹ הַמֶּלֶךְ. וּמָה אַתָּה מְבַקֵּשׁ, שֶׁאֶתְרַצֶּה לָהּ, הָבֵא הַנְּיָר וְהַלַּבְלָר מִשֶּׁלְּךָ, וַהֲרֵי כְּתַב יָדִי. כָּךְ אָמַר מֹשֶׁה לַהַקָּדוֹשׁ בָּרוּךְ הוּא כְּשֶׁעָשׂוּ יִשְׂרָאֵל אוֹתוֹ מַעֲשֶׂה. אֵין אַתָּה יוֹדֵעַ מֵאֵיזֶה מָקוֹם הוֹצֵאתָ אוֹתָם, מִמְּקוֹם עֲבֹדָה זָרָה. אָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא. וּמָה אַתָּה מְבַקֵּשׁ, שֶׁאֶתְרַצֶּה לָהֶם, הָבֵא הַלּוּחוֹת מִשֶּׁלְּךָ, וַהֲרֵי כְּתַב יָדִי. אָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא. חַיֶּיךָ, כְּשֵׁם שֶׁנָּתַתָּ נַפְשְׁךָ עֲלֵיהֶם בָּעוֹלָם הַזֶּה, אַף לֶעָתִיד לָבוֹא, כְּשֶׁאָבִיא לָהֶם אֶת אֵלִיָּהוּ זָכוּר לַטּוֹב, שְׁנֵיכֶם בָּאִים כְּאֶחָד, שֶׁנֶּאֱמַר (נחום א, ג) "ה' בְּסוּפָה וּבִשְׂעָרָה דַּרְכּוֹ", "בְּסוּפָה", זֶה מֹשֶׁה דִּכְתִיב "וַתָּשֶׂם בַּסּוּף עַל שְׂפַת הַיְאֹר", "וּבִשְׂעָרָה", זֶה אֵלִיָּהוּ דִּכְתִיב (מלכים ב ב, יא) "וַיַּעַל אֵלִיָּהוּ בַּסֳעָרָה הַשָּׁמָיִם", אוֹתָהּ שָׁעָה הוּא בָּא וּמְנַחֵם אֶתְכֶם, שֶׁנֶּאֱמַר (מלאכי ג, כג כד) "הִנֵּה אָנֹכִי שֹׁלֵחַ לָכֶם אֵת אֵלִיָּה הַנָּבִיא וְגוֹ' וְהֵשִׁיב לֵב אָבוֹת עַל בָּנִים". (כָּתוּב בְּרֶמֶז.