וַיִּקְח֞וּ אֶת־פִּ֣יחַ הַכִּבְשָׁ֗ן וַיַּֽעַמְדוּ֙ לִפְנֵ֣י פַרְעֹ֔ה וַיִּזְרֹ֥ק אֹת֛וֹ מֹשֶׁ֖ה הַשָּׁמָ֑יְמָה וַיְהִ֗י שְׁחִין֙ אֲבַעְבֻּעֹ֔ת פֹּרֵ֕חַ בָּאָדָ֖ם וּבַבְּהֵמָֽה׃
И взяли сажу из печи и встали пред фараоном; и Моисей бросил его в небо; и это стало кипением, разрывающимся с блеснами на человеке и на животном.
Ibn Ezra
Go to Pharaoh, to his palace. Rabbi Yehudah HaLevi said: There were two plagues involving water, one that the river turned to blood and all the fish died, and one that the frogs came out of the river. There were two plagues on land, the lice and the mixture of wild animals, as the verse states (Bereishis 1:24): “Let the earth bring forth living creatures.” Two were in the air, for pestilence was abnormal heat or chill that caused countless livestock to die at once, since all life depends on the atmosphere. The second one was the plague of rash, for the Torah calls the sky above their head the heavens (and Moshe began the plague of rash by throwing the furnace soot heavenward). The seventh plague (hail) was a mixture of the sphere of storm and fire, as the Torah describes (9:24): “There was hail and fire flashing among the hailstones.” The eighth plague, locusts, came from far away by means of the wind. The ninth one was a wondrous plague, in which the light of the luminaries and the stars disappeared from the land of Egypt. In the tenth, the destroyer came down from the sphere of splendor to kill the first born”.
Rashi
וכל רכב מצרים signifies AND with these were ALL THE other CHARIOTS OF EGYPT. And whence came all these animals required for the chariots? If you say that they were from the cattle of the Egyptians — but you know it is stated, (Exodus 9:6) “And all the cattle of the Egyptians died”. And if you say that they were from the Israelites’ cattle — but is it not stated, (Exodus 10:26) “Our cattle, also, shall go with us”! Then whose were they? They were of those “who feared the word of the Lord” and saved their cattle by bringing them into their stables (Exodus 9:20). Deriving it from here (on account of this fact) R. Simeon said: The best amongst the Egyptians — kill him (otherwise he will afterwards devise evil against you); the best amongst the serpents — crush its brains (Mekhilta).