The passage examines textual difficulties in the account of Pharaoh's pursuit of the Israelites, explaining that the Egyptians pursued Israel because their heavenly guardian angel accompanied them, just as a national guardian typically helps his people in battle.
אָכֵן יִתְבָּאֵר עַל פִּי דִּבְרֵיהֶם זִכְרוֹנָם לִבְרָכָה (שמות רבה כא,ה) שֶׁאָמְרוּ וְזֶה לְשׁוֹנָם: ״וּמִצְרַיִם נוֹסֵעַ אַחֲרֵיהֶם״ – זֶה שַׂר שֶׁל מִצְרַיִם, מִצְרַיִם שְׁמוֹ, עַד כָּאן לְשׁוֹנָם. וְהִנֵּה הַמַּלְאָךְ הַלָּז בָּא עִמָּהֶם, כִּי כֵן הוּא הַנָּהוּג שֶׁהַשַּׂר יַעֲזֹר לְאֻמָּתוֹ וְיִפּוֹל בִּנְפִילָתָהּ, וְצֵא וּלְמַד מִמַּעֲשֵׂה אֲלֶכְּסַנְדְּרוּס מוּקְדוֹן (יומא סט:) שֶׁהָיָה נִדְמֶה לוֹ שָׂרוֹ בַּמִּלְחָמוֹת. וְהִנֵּה מִן הַסְּתָם כִּי הַשַּׂר יִהְיֶה עוֹמֵד לִימִין הַמֶּלֶךְ, לֹא לִפְנֵי הָעָם, וְהִנֵּה מִסֵּדֶר הָרָגִיל בַּמִּלְחָמוֹת שֶׁהַמֶּלֶךְ בֵּינֵיהֶם – שֶׁהָעָם יַקְדִּימוּ קֹדֶם לַמֶּלֶךְ וְהַמֶּלֶךְ לְבַסּוֹף מֵהָעָם. וְכָאן הוֹדִיעַ הַכָּתוּב הַדָּבָר שֶׁמִּמֶּנּוּ בָּאָה הַהַרְגָּשָׁה לְיִשְׂרָאֵל לִירֹא וּלְפַחֵד, הֲגַם שֶׁקָּדַם לָהֶם מַה שֶׁקָּדַם מֵהַיְדִיעָה, וְאָמַר וּפַרְעֹה הִקְרִיב, פֵּרוּשׁ, לֹא עָשָׂה סֵדֶר הָרָגִיל לְהַקְדִּים הָעָם אֶלָּא הִקְרִיב עַצְמוֹ קֹדֶם לָעָם. וַיִּשְׂאוּ בְנֵי יִשְׂרָאֵל אֶת עֵינֵיהֶם וְהִנֵּה מִצְרַיִם, פֵּרוּשׁ, שַׂר שֶׁל מִצְרַיִם כַּנִּזְכָּר. פֵּרוּשׁ, לְצַד שֶׁפַּרְעֹה הִקְרִיב וְהַשַּׂר הָיָה לְפָנָיו עוֹמֵד, זֶה הָיָה סִבָּה לִרְאוֹת יִשְׂרָאֵל הַשַּׂר שֶׁשְּׁמוֹ מִצְרַיִם נוֹסֵעַ וְגוֹ׳, וְהֵם לֹא יוּכְלוּ דַּעַת סִבַּת הַשַּׂר שֶׁאֵינוֹ אֶלָּא לַעֲמֹד לִפְנֵי מֶלֶךְ כַּנָּהוּג, כִּי אֵין מִנְהַג הַמֶּלֶךְ לְהַקְדִּים לַמַּחֲנֶה, וְהֵם רָאוּ הַשַּׂר נוֹסֵעַ אַחֲרֵיהֶם, פֵּרוּשׁ, קֹדֶם הַמַּחֲנֶה. לָזֶה רָעֲשׁוּ כִּי חָשְׁבוּ כִּי שָׂרֵי מַעְלָה בָּאוּ לַעֲרֹךְ עִמָּם מִלְחָמָה, וַהֲגַם שֶׁקָּדַם לָהֶם מַה שֶׁקָּדַם לֹא הִסְפִּיק לָהֶם כְּשֶׁרָאוּ מַלְאָכִים בָּאוּ לְהִלָּחֵם עִמָּהֶם, כִּי הוּא אוֹת כִּי ה׳ חָזַר מִמַּחֲשַׁבְתּוֹ הַטּוֹבָה, כִּי זוּלַת זֶה לֹא הָיָה מַסְכִּים עַל מַלְאָכוֹ לָבֹא כְּנֶגְדָּם, וְלָזֶה צָעֲקוּ וְגוֹ׳. וְאִלּוּ לֹא הָיָה פַּרְעֹה מַקְדִּים, אוֹ אִם הָיָה סֵדֶר הָרָגִיל שֶׁיַּקְדִּים הַמֶּלֶךְ, הֵם הָיוּ תּוֹלִים הַדָּבָר כִּי לֹא לְמִלְחָמָה בָּא אֶלָּא לַעֲמֹד לִפְנֵי הַמֶּלֶךְ כְּחֹק שָׂרֵי מַעְלָה עִם כָּל מְלָכִים אֲשֶׁר הֵם מְמֻנִּים עֲלֵיהֶם, וְלֹא הָיוּ מְפַחֲדִים. וּבָזֶה נִתְיַשֵּׁב הָעִנְיָן וְיִשּׁוּב הַכְּתוּבִים. וְטַעַם שֶׁלֹּא מָנַע ה׳ הַמַּלְאָךְ מִבֹּא, לִשְׁנֵי טְעָמִים: הָאֶחָד, כְּדֵי לְהָרְגוֹ לִפְנֵיהֶם, כְּאָמְרוֹ ״וַיַּרְא יִשְׂרָאֵל אֶת מִצְרַיִם מֵת עַל שְׂפַת הַיָּם״, וְאָמְרוּ זִכְרוֹנָם לִבְרָכָה (זהר ח״ב נב:) שֶׁיְּכַוֵּן עַל הַשַּׂר שֶׁשְּׁמוֹ מִצְרַיִם. וְטַעַם שֵׁנִי, אֱלֹהִים חֲשָׁבָהּ לְטוֹבָה כְּדֵי שֶׁיִּפְחֲדוּ וְיַחְזְרוּ בִּתְשׁוּבָה שְׁלֵמָה וִיקָרְבוּ לִבָּם לַשָּׁמַיִם, כְּדֵי שֶׁבְּאֶמְצָעוּת זֶה יַעֲשֶׂה ה׳ לָהֶם הַנֵּס הֶעָצוּם שֶׁל קְרִיעַת יַם סוּף, וְדָבָר זֶה לֹא הֻבְטְחוּ בּוֹ קוֹדֶם. וְתִמְצָא שֶׁדָּרְשׁוּ זִכְרוֹנָם לִבְרָכָה (שמות רבה כא,ה) בְּתֵבַת ״הִקְרִיב״ וְלֹא אָמַר ״קָרַב״, יִרְצֶה שֶׁהִקְרִיב לִבָּן שֶׁל יִשְׂרָאֵל לַאֲבִיהֶם שֶׁבַּשָּׁמַיִם, וְכֵן הָיָה דִּכְתִיב וַיִּצְעֲקוּ בְנֵי יִשְׂרָאֵל אֶל ה׳:
We must fall back on what our sages have taught as described in Shemot Rabbah 21,5 that when the Israelites noticed Pharaoh pursuing them they naturally turned their eyes heavenwards expecting G'd to manifest Himself and to smite the Egyptians. Imagine the Israelites' surprise when what they saw was the guardian angel of Egypt whose name is Mitzrayim flying through the air. It was then that they became afraid as they realised that this angel had now come out in order to help his protegees, the Egyptians. It is an accepted theory that the fortunes of these guardian angels are bound up with their charges. When the protegees of such guardian angels suffer a defeat so does the guardian angel himself. [In fact according to the Kabbalists when G'd wants to destroy a people, He first destroys their guardian angel. After that, even if the people appear still to be going strong, their fate has already been sealed. Ed.] We are told in Yuma 69 that Alexander the Great was in the habit of observing the guardian angel of Macedonia at work whenever he went into battle. It is customary for a minister to take up position on the right side of the king and not in front of the people. Normally, a king who travels into battle with his troops takes up his position behind the infantry. In this instance the Israelites had the impression that the guardian angel of Egypt was still going strong, far from being the first one to be defeated by G'd. The Torah also describes Pharaoh הקריב, as coming close, i.e. travelling ahead of his troops not behind them. The reason the Israelites were able to see the guardian angel of Egypt at all was because the guardian angel was positioned next to the king who travelled ahead of his troops. This unusual spectacle frightened the Israelites. They believed that celestial forces were now arraigned against them. In view of all this, the fact that G'd had told them that the Egyptians would pursue them and He would deal harshly with Pharaoh was no longer enough for the people to keep their cool. There were two reasons why G'd had not interfered with the guardian angel at that time. 1) G'd was looking for a legal excuse to kill that guardian angel. The Zohar, section two, page 52 interprets 14,30 "Israel saw Mitzrayim dead on the beaches of the sea," as a reference to the guardian angel of Egypt. The second reason G'd allowed the guardian angel of Egypt to adopt such a visibly threatening posture was for Israel's benefit. G'd wanted Israel to do תשובה, to repent. They needed to acquire the merit of repentance in order to justify that G'd should perform the great miracle of splitting the Sea of Reeds on their behalf. This was something G'd had not promised them previously. Shemot Rabbah 21,5 also points out that the unusual form (causative) ופרעה הקריב "and Pharaoh caused himself to come close," instead of the usual ופרעה קרב, "and Pharaoh approached," is a clear indication of G'd's purpose being to cause the Israelites to do תשובה. In the event, G'd's expectations were fulfilled as the Torah reports that "the children of Israel cried out to G'd" (14,10).