רַבִּי עֲקִיבָא אוֹמֵר: מִנַּיִן שֶׁכָּל מַכָּה וּמַכָּה שֶהֵבִיא הַקָּדוֹשׁ בָּרוּךְ הוּא עַל הַמִּצְרִים בְּמִצְרַיִם הָיְתָה שֶׁל חָמֵשׁ מַכּוֹת? שֶׁנֶּאֱמַר: יְִשַׁלַּח בָּם חֲרוֹן אַפּוֹ, עֶבְרָה וָזַעַם וְצַרָה, מִשְׁלַחַת מַלְאֲכֵי רָעִים. חֲרוֹן אַפּוֹ - אַחַת, עֶבְרָה - שְׁתָּיִם, וָזַעַם - שָׁלוֹשׁ, וְצָרָה - אַרְבַּע, מִשְׁלַחַת מַלְאֲכֵי רָעִים - חָמֵשׁ. אֱמוֹר מֵעַתָּה: בְּמִצְרַיִם לָקוּ חֲמִשִּׁים מַכּות, וְעַל הַיָּם לָקוּ חֲמִשִּׁים וּמָאתַיִם מַכּוֹת.

Rabbi Akiva says, says, "From where [can you derive] that every plague that the Holy One, blessed be He, brought upon the Egyptians in Egypt was [composed] of five plagues? As it is stated (Psalms 78:49): 'He sent upon them the fierceness of His anger, wrath, and fury, and trouble, a sending of messengers of evil.' 'The fierceness of His anger' [corresponds to] one; 'wrath' [brings it to] two; 'and fury' [brings it to] three; 'and trouble' [brings it to] four; 'a sending of messengers of evil' [brings it to] five. You can say from here that in Egypt, they were struck with fifty plagues; and at the Sea, they were struck with two hundred and fifty plagues."