"And Aaron's staff swallowed their staffs." Rabbi Elazar said: a miracle within a miracle. It is written, "Pharaoh's heart was hardened" (Exodus 7:14). They said: to what may the matter be compared? To a lion and beasts and a fox who were traveling in a ship, and a donkey was collecting toll from the ship. The donkey said to them: Give me toll. The fox said to the donkey: How brazen you are! Do you not know that the king of the beasts is with us, and yet you demand toll? The donkey said to him: From the king I take it, and into his treasury I deposit it. The lion said: Bring the ship close to me. He went out and tore the donkey apart and gave it to the fox. He said to him: Arrange for me the limbs of this fool. The fox went and arranged them. He saw its heart, took it, and ate it. When the lion came, he found its limbs laid out. He said to him: Where is the heart of this fool? He said to him: My lord the king, it had no heart, for if it had a heart it would not have taken toll from the king. So too the wicked Pharaoh: if he had a heart he would not have said to the King of the kings of kings, Give me a gift, and he would not have forgotten what the mice did to him, and still he was saying, "Who is the LORD that I should heed His voice? I do not know the LORD" (Exodus 5:2).
A Miracle Within a Miracle and the Donkey Without a Heart
Yalkut Shimoni on Torah 182:2
וַיִּבְלַע מַטֵּה אַהֲרֹן אֶת מַטֹּתָם. אָמַר רַבִּי אֶלְעָזָר, נֵס בְּתוֹךְ נֵס. (שמות ז יד) כְּתִיב כָּבֵד לֵב פַּרְעֹה. אָמְרוּ, לְמָה הַדָּבָר דּוֹמֶה, לְאֲרִי וְחַיּוֹת וְשׁוּעָל שֶׁהָיוּ הוֹלְכִין בִּסְפִינָה, וַחֲמוֹר גּוֹבֶה מֶכֶס מִן הַסְּפִינָה, אָמַר לָהֶם הַחֲמוֹר, תְּנוּ לִי מֶכֶס, אָמַר לוֹ שׁוּעָל לַחֲמוֹר, כַּמָּה עַזִּין פָּנֶיךָ, אַתָּה יוֹדֵעַ שֶׁמֶּלֶךְ שֶׁבַּחַיּוֹת עִמָּנוּ וְאַתָּה תִּשְׁאַל מֶכֶס, אָמַר לוֹ הַחֲמוֹר, מִן הַמֶּלֶךְ אֲנִי נוֹטֵל וְלִגְנָזָיו אֲנִי מַכְנִיס, אָמַר לוֹ הָאֲרִי, קָרְבוּ לִי הַסְּפִינָה, וְיָצָא וּטְרָפוֹ לַחֲמוֹר וּנְתָנוֹ לַשּׁוּעָל, אָמַר לוֹ, סַדֵּר לִי אֵבָרָיו שֶׁל שׁוֹטֶה זֶה, הָלַךְ הַשּׁוּעָל וְסִדְּרָן, רָאָה לִבּוֹ נְטָלוֹ וַאֲכָלוֹ, כְּשֶׁבָּא הָאֲרִי מָצָא אֵבָרָיו נְתוּחִין, אָמַר לוֹ, לִבּוֹ שֶׁל שׁוֹטֶה זֶה הֵיכָן הוּא, אָמַר לוֹ, אֲדוֹנִי הַמֶּלֶךְ, לֹא הָיָה לוֹ לֵב, שֶׁאִם הָיָה לוֹ לֵב לֹא הָיָה נוֹטֵל מֶכֶס מִן הַמֶּלֶךְ. אַף כָּךְ פַּרְעֹה הָרָשָׁע, אִם הָיָה לוֹ לֵב לֹא הָיָה אוֹמֵר לְמֶלֶךְ מַלְכֵי הַמְּלָכִים תֵּן לִי דוֹרוֹן וְשָׁכַח מַה שֶּׁעָשׂוּ לוֹ הָעַכְבָּרִים, וַעֲדַיִן הָיָה אוֹמֵר (שמות ה, ב) "מִי ה' אֲשֶׁר אֶשְׁמַע בְּקֹלוֹ לֹא יָדַעְתִּי אֶת ה'".