Matthew Poole and continuators on Isaiah 8:7

7 Now therefore behold, the LORD bringeth up upon them the waters of the river strong and many, even the king of Assyia, and all his glory : and he shall come up over all his chanels , and go over all his banks.

Because they despise the Opposition which they have from Siloah and Ierusalem, they shall have a more potent Enemy.

Upon Israel. See on the foregoing Verse.

Of Euphrates, oft called the river, for its eminent greatness: Whereby he understands the Assyrian Forces, as the next Words explain the Metaphor.

His numerous and puissant Army, in which he gloried. See Isa. 10. 8.

This great River shall overflow its own proper Channels. The meaning is, This great Monarch shall enlarge his Dominions, and add the Lands of Syria and Israel to them. Some render the Words, he shall come up with all his channels or streams; for the Hebrew Particle al sometimes signifies with, as Iob 38. 32. But it seems hard to understand the same Particle one way in this Clause, and another in the last Clause. Besides, the last Clause favours the former Interpretation, the same thing being repeated in it, as is usual in the Sacred Writings. Or, this may be understood of the Channels and Banks of the People or Land of Israel. The Enemy being represented under the Metaphor of a River breaking in upon their Land, may fitly be said to overflow all their Channels and Banks, to wit, all Places both low and high, so that nothing shall be able to withstand his Fury.