I have digged and drunk strange waters, and with the sole of my feet have I dried up all the rivers of besieged places.

Wesley's Notes

19:24 Strange waters - Such as were never discovered by others. Dried up - And as I can furnish my army with water digged out of the earth; so I can deprive my enemies of their water, and can dry up their rivers, and that with the sole of my feet; with the march of my vast and numerous army, who will easily do this, either by marching through them, and each carrying away part with them: or by making new channels, and driving the waters of the river into them.

King James Translators' Notes

besieged: or, fenced

Matthew Henry's Concise Commentary

19:20-34 All Sennacherib's motions were under the Divine cognizance. God himself undertakes to defend the city; and that person, that place, cannot but be safe, which he undertakes to protect. The invasion of the Assyrians probably had prevented the land from being sown that year. The next is supposed to have been the sabbatical year, but the Lord engaged that the produce of the land should be sufficient for their support during those two years. As the performance of this promise was to be after the destruction of Sennacherib's army, it was a sign to Hezekiah's faith, assuring him of that present deliverance, as an earnest of the Lord's future care of the kingdom of Judah. This the Lord would perform, not for their righteousness, but his own glory. May our hearts be as good ground, that his word may strike root therein, and bring forth fruit in our lives.