Amos 8:8

"Shall not the land tremble for this, and every one mourn that dwelleth therein? yea, it shall rise up wholly like the River; and it shall be troubled and sink again, like the River of Egypt."

It seems rather strange to compare the trembling of the earth with the rising and falling of the Nile River (as most interpret this), "because the rise and fall of the Nile River are quite gradual."[21] However, since the devastation caused by the Nile at flood (rising some 20 feet)[22] was tremendous, it is an apt figure of the overwhelming destruction in store for Israel. Thus, it would appear better to understand "tremble" as a metaphor for such a disaster, instead of "literally" as an earthquake, which does not seem to be indicated at all. There may be something else here. Dummelow pointed out the fact followed by most interpreters that the word for "River" used in this place is regularly employed for the Nile";[23] but Barnes noted that, "It is the Egyptian name for river which Israel brought with them out of Egypt, and is used either for the Nile, or for one of the artificial trenches derived from it,"[24] hence, by extension (through time) as the name of any river.

In this light, we interpret the verse as a reference to two rivers, not merely one, the application above pertaining to the second river, which was surely the Nile; but the other river is the one mentioned by Isaiah:

"Now, behold, therefore the Lord bringeth upon them the waters of the River, strong and mighty, even the king of Assyria and all his glory: and it shall come up over all its channels, and go over all its banks, and it shall sweep onward and pass into Judah; it shall overflow and pass through (Isaiah 8:5-8)."

It will be noted that "River" in the first part of this verse is definitely not referred to as the "River of Egypt." Also, the fact that Assyria is clearly in the mind of Amos throughout this prophecy adds to the probability of their being two rivers in view. In that case, it would mean that the River (Assyria) would overflow against Israel in a manner ("as") like the well-known innundations of the Nile, "of Egypt" in that case being the identification of the river to which comparison was made, and not an identification of the first river.