John Calvin 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 shall dig and drink water. The tyrant still goes on to boast of his strength, and threatens that he will bring so powerful an army that by their numbers he will dry up all the fountains and rivers. Yet, when he says, With the sole of my feet I shall dry up all the lakes of the siege, by the lakes of the siege some understand the fountain of Siloah, and the cisterns and pools from which the besieged Jews could not be deprived without being consumed by thirst.

And, indeed, in the former clause he appears to say that, though the whole country were dry, still he does not dread a scarcity of water, because his vast military forces will be abundantly able to dig wells. In the second clause he adds, that he will have the means at his command to dry up all the waters of the city, so as to slay the Jews by thirst.

In short, he means that Jerusalem will be unable to resist the siege, and will not be able to hold out any longer, but must immediately surrender. But while wicked men boast in this way, God sits in heaven, from which he will eventually execute judgment against them; for this narrative of the Prophet is intended to lead us to consider the stupendous judgment of God against that tyrant.