Charles Ellicott Commentary Isaiah 37:25

"I have digged and drunk water, and with the sole of my feet will I dry up all the rivers of Egypt." — Isaiah 37:25 (ASV)

I have digged, and drunk water ... —This, again, was one of the common boasts of the Assyrian conquerors. It was Sennacherib’s special glory, as recorded in his inscriptions, that he had provided cities with water which were previously scantily supplied, that he had made wells even in the deserts (Records of the Past, i. 29, 31, 9:23).

All the rivers of the besieged places. —As the words stand, they suggest the thought that the Assyrian army could cut off the supply of water as well as provide it, and so connect themselves with the Rabshakeh’s taunt in Isaiah 36:12. Their true meaning, however, is probably, as in Isaiah 19:6; Micah 7:12, “the rivers or canals of Egypt,” a form being used for Egypt which also conveys the idea of “besieged fortresses.” So taken, the words are a defiant threat against Tirhakah. Not all the branches of the Nile in the Delta would protect his cities. His armies would, as it were, dry them up.