Midrash su Geremia 46:22

When Pharaoh shall speak unto you, saying (Exod. 7:9). May it please our masters to teach us whether a man who is bitten by a serpent while standing in prayer may stop praying. Our masters teach us: A man standing in prayer may not respond to the greeting of a king, nor may he stop praying when a serpent encircles his heel. Once a wild ass attacked and bit R. Hanina the son of Dosa while he was standing in prayer and his disciples fled in fear. Upon their return a hour later, they found the ass lying dead near its den. They cried out: “Woe to the man whom a wild ass bites, but woe to the wild ass that attacks R. Hanina the son of Dosa.” Why did the sages compare a serpent that winds itself about the heel of a man with the kingdom of Egypt? R. Yosé the son of Pazzi said: Because it is written: The sound thereof shall go like the serpent’s; for they march with an army, and come against her with axes, as hewers of wood (Jer. 46:22). Just as the serpent hisses and kills, so the kingdom of Egypt hisses and kills a man. He would imprison a man, accuse him in secret, and surreptitiously execute him.

“As when a man fled from the lion and a bear attacked him; he came home and leaned his hand on the wall, and a snake bit him” (Amos 5:19).
Rabbi Yuda son of Rabbi Simon began: “As when a man fled from the lion and a bear attacked him; he came home and leaned his hand on the wall, and a snake bit him.” Rabbi Huna and Rabbi Aḥa in the name of Rabbi Ḥama bar Rabbi Ḥanina said: “As when a man fled from the lion,” that is Babylonia, according to: “The first was like a lion” (Daniel 7:4); “and a bear attacked him,” that is Media, according to: “And behold, another beast, a second one, resembling a bear” (Daniel 7:5).
Rabbi Yoḥanan said: le dev is written [“a second one, resembling a bear (dov)].”⁹ The words in the verse in Daniel 7:5 domeh le-dov, “resembling a bear,” could be vocalized domeh le-dev, meaning resembling a wolf, as dev can mean wolf in Aramaic. This is the opinion of Rabbi Yoḥanan, as Rabbi Yoḥanan said: “Therefore, a lion from the forest smote them” (Jeremiah 5:6), that is Babylonia; “a wolf of the deserts will plunder them” (Jeremiah 5:6), that is Media; “a leopard lies in wait near their cities” (Jeremiah 5:6), that is Greece; “everyone who emerges from them will be mauled” (Jeremiah 5:6), that is Edom; “he comes home” (Amos 5:19), that is Greece when the Temple stood; “and a snake bit him” (Amos 5:19), that is Edom, as it is stated: “Its sound will go forth like a snake” (Jeremiah 46:22).
Likewise, it says: “Open for me, my sister, my love, my dove, my faultless one,” (Song of Songs 5:2). “Open for me, my sister,” that is Babylonia; “my love,” that is Media; “my faultless one,” in Greece; “my dove,” in Edom, as throughout the days of Greece[’s hegemony] the Temple was standing and Israel was offering doves and pigeons on the altar.
Rabbi Pinḥas and Rabbi Levi in the name of Rabbi Ḥama bar Ḥanina offered an interpretation [of “In my distress I called to the Lord and to my God I cried; from His Sanctuary He heard my voice, and my cry before Him came into His ears” (Psalms 18:7)]: It is written: “In my distress I called to the Lord,” in Babylonia; “and to my God I cried,” in Media; from His Sanctuary He heard my voice,” in Greece, as Rabbi Huna himself said: “My dove,” in Greece, as throughout the days of Greece, the Temple was standing and Israel was offering there doves and pigeons on the altar. That is: “from His Sanctuary He heard my voice and my cry before Him came into His ears,” in the kingdom of Edom.
Another matter: “ As when a man fled from the lion,” that is Nebuchadnezzar; “and a bear attacked him,” that is Belshatzar; “he came home and leaned his hand on the wall, and a snake bit him,” that is Haman, who would crush the people like a snake. That is as it is written: “Reḥum the commander and Shimshai the scribe” (Ezra 4:8), that is the son of Haman; “wrote a letter…to Artaxerxes the king, as follows” (ibid.). And what was written in it? “Now issue a decree to cease, and that this city not be rebuilt ….” (Ezra 4:21), [“they will no longer pay] minda” (Ezra 4:13), that is land tax; “belo” (ibid.), that is the poll tax; and “halakh” (ibid.), that is the king’s service; “and the revenue of the kings will be harmed” (ibid.). Rav Huna and Rabbi Pinḥas said: Even things with which the kingdom entertains itself, e.g., theaters and circuses, this people harms. When he sent it, it was received by the king, and he canceled work on the Temple. When they saw that, everyone began screaming: 'Woe [vai];' “it was [vayhi] during the days of Aḥashverosh” (Esther 1:1).

3. "And cast it down before Pharaoh and it shall be a serpentine creature." It was taught in a Tannaitic statement: "One who stands to pray, even if the king should inquire of his welfare, should not answer. And even if a snake is wrapped around his ankles, he should not decease [prayer]. What did the sages see to connect this circling behavior of the snake to the sovereign of Egypt? Rabbi Simeon son of Pazi says that because it is written "Its voice like a snake travels" (Jeremiah 46:22) Just like the snake silences and kills, so too, the Kingdom of Egypt silences and kills. This is because it puts [a person] in prison and silences him in order to kill him. Another interpretation: What did the Holy One, Source of All Blessing is He see to connect the Kingdom of Egypt to a snake? Just like a serpent twists its path [slithers] so too Pharaoh twists his path [i.e. acts in a manner most wicked as opposed to the straight and narrow]. Therefore, the Holy One, Source of all Blessing is He said to Moses: Just like a snake twists, so does Pharaoh twist. When Pharaoh attempts to twist, speak to Aaron and he will suspend [raise] the staff against him [Pharaoh]. [As a message to Pharaoh that] from this you shall be struck.