The city of waters - This refers to the lower town of Rabbah (modern-day Amman), so named because of a stream that rises within it and flows…

And Joab sent messengers to David
To acquaint him how he had proceeded, and what success he had had:

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To be this severe in putting the children of Ammon to slavery was a sign that David's heart was not yet softened by repentance, when this took plac…