Midras Yehezkiel 31:3: Mekhilta DeRabbi Yishmael, Midrash Tanchuma, Shir HaShirim Rabbah & Shemot Rabbah

When the (other) kingdoms are symbolized, they are symbolized as cedars, viz. (Ezekiel 31:3) "Behold, Ashur, a cedar in the Levanon," and (Amos 2:9) "And I destroyed the Emori from before them, whose height was as the height of cedars, etc.", and (Daniel 4:17) "The tree (Bavel) that you have seen, etc." And when Egypt is symbolized, it is symbolized only as stubble, viz. "He will consume them as stubble." And when the (other) kingdoms are symbolized, they are symbolized as silver and gold (Ibid. 2:32) "This statue, its head of fine gold, etc." And when Egypt is symbolized, it is symbolized only as lead, viz. (Exodus 15:10) "they sank as lead." And when the (other) kingdoms are symbolized, they are symbolized as beasts, viz. (Daniel 7:3) "and four immense beasts, etc." And when Egypt is symbolized, it is symbolized only as a fox, viz. (Song of Songs 2:15) "Seize for us the foxes, etc."

Sennacherib erected his palace in Lebanon with certain protective devices, between two lofty mountains, but wells sprang forth out of the mountains, tore the palace from its foundations, and bore it away, as it is said: Behold, the Assyrian was a cedar in Lebanon with fair branches, and with a shadowy shroud, and of a high stature, and its top was among the thick boughs. The water nourished it; the deep made it grow (Ezek. 31:3–4). And it says also: Thus was it fair in its greatness, in the length of its branches; for its root was by many waters (ibid., v. 7), and it states: I have digged and drunk waters, and with the sole of my feet have I dried up all the rivers of Egypt (Isa. 37:25). What was his ultimate end? Thus said the Lord God: in the day when he went down to the netherworld I caused the deep to mourn and cover itself for him (Ezek. 31:15).

Sennacherib erected his palace in Lebanon with certain protective devices, between two lofty mountains, but wells sprang forth out of the mountains, tore the palace from its foundations, and bore it away, as it is said: Behold, the Assyrian was a cedar in Lebanon with fair branches, and with a shadowy shroud, and of a high stature, and its top was among the thick boughs. The water nourished it; the deep made it grow (Ezek. 31:3–4). And it says also: Thus was it fair in its greatness, in the length of its branches; for its root was by many waters (ibid., v. 7), and it states: I have digged and drunk waters, and with the sole of my feet have I dried up all the rivers of Egypt (Isa. 37:25). What was his ultimate end? Thus said the Lord God: in the day when he went down to the netherworld I caused the deep to mourn and cover itself for him (Ezek. 31:15).