Midrash su Salmi 77:19

THE GATHERING OF THE WATERS
ON the third day all the earth was flat like a plain and the waters covered the surface of all the earth. When the word of the Almighty was uttered, "Let the waters be gathered together" (Gen. 1:9), the mountains and hills arose from the ends of the earth and they were scattered over the surface of all the earth, and valleys were formed over the inner parts of the earth; and the waters were rolled together and gathered into the valleys, as it is said, "And the gathering together of the waters he called seas" (Gen. 1:10). Forthwith the waters became proud and they arose to cover the earth as at first, when the Holy One, blessed be He, rebuked them || and subdued them, and placed them beneath the soles of His feet, and measured them with the hollow of His hand that they should neither decrease nor increase. He made the sand as the boundary of the sea, just like a man who makes a fence for his vineyard. When they rise and see the sand before them they return to their former place, as it is said, "Fear ye not me? saith the Lord: will ye not tremble at my presence, which have placed the sand for the bound of the sea?" (Jer. 5:22).

And He took off their chariot wheels (Exod. 15:25). R. Johanan said: The heavenly fire from above ignited the wheels below, and the yokes and the chariots, which were made of silver, gold, precious stones, and pearls, were melted together. This occurred so that Israel might take the spoils with them. R. Nehemiah stated: The roar of the heavenly thunder caused the water ducts below to fly asunder, as it is said: The voice of Thy thunder was in the whirlwind (Ps. 77:19). Previously the mules had pulled the chariots, but now the chariots dragged the mules into the mire. He dealt harshly with them because the Egyptians had said: Let the heavier work be laid upon the men (Exod. 5:9).

(Exodus 14:25) "And He removed their chariot wheels": R. Yehudah says: Because of the fire on high, the wheels below were broken, the yokes and the chariots ran of themselves, being filled with vessels of silver and gold and precious gems and pearls for Israel to take as spoil. R. Nechemiah says: Because of the thunders on high, the pivots below flew off, viz. (Psalms 77:19) "The rumble of your thunder caught the wheel; lightings lit the world", and the yokes and the chariots ran of themselves. In the past, the mules would pull the chariots. Now, the chariots were pulling the mules. "and He led them with hardness": R. Yehudah says: As they meted it out, so did He mete it out to them. (Exodus 5:9) "Let the labor be hard on the men" — "and He led them with hardness." "And Egypt said: 'I shall flee from before Israel'": The wicked and the fools among them said: "Shall we flee these toils and tempests?" The sober among them said: "I shall flee from before Israel, for the L rd wars for them against the Egyptians." They realized that He who wrought miracles for them in Egypt was doing so at the sea. R. Yossi says: Whence do you derive that with the plagues that these were plagued at the sea, the others were plagued in Egypt and that they saw each other (at the time)? From "And Egypt said: "I (at the sea) shall flee from before Israel; for the L rd is warring for them in Egypt (too)!" And (this obtains) not with Egypt alone, but with all who afflict Israel throughout the generations. As it is written (Psalms 78:66) "And He beat back His foes. Eternal disgrace did He inflict upon them, viz. (Psalms 81:15-16) "In a moment I would humble their foes … and their time (of punishment) will be eternal", and (Isaiah 14:25) "to break Ashur in My land, etc." And thus, throughout the generations, viz. (Ibid. 26) "this is the counsel for all of the earth, and this is the hand stretched forth against all the nations" (that afflict Israel). Why so? (Ibid. 27) "For the L rd of hosts has counseled, and who will annul it? And His hand is stretched forth, and who will turn it back?" Not Egypt ("Mitzrayim") alone, then, (is intended), but all who afflict ("meitzarim") them, throughout the generations. Thus — "for the L rd wars for them against Mitzrayim (- "meitzarim").