Adam Clarke on 2 Samuel 12:1

There were two men in one city - See a discourse on fables at the end of Jdg 9:56 (note), and a discourse on parabolic writing at the end of the thirteenth chapter of Matthew.

There is nothing in this parable that requires illustration; its bent is evident; and it was construed to make David, unwittingly, pass sentence on himself. It was in David's hand, what his own letters were in the hands of the brave but unfortunate Uriah.