A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
2 Kings (2 Samuel) 12:1
sa2 12:1NATHAN'S PARABLE. (Sa2 12:1-6)
the Lord sent Nathan unto David--The use of parables is a favorite style of speaking among Oriental people, especially in the conveyance of unwelcome truth. This exquisitely pathetic parable was founded on a common custom of pastoral people who have pet lambs, which they bring up with their children, and which they address in terms of endearment. The atrocity of the real, however, far exceeded that of the fictitious offense.
2 Kings (2 Samuel) 12:5
sa2 12:5the man that hath done this thing shall surely die--This punishment was more severe than the case deserved, or than was warranted by the divine statute (Exo 22:1). The sympathies of the king had been deeply enlisted, his indignation aroused, but his conscience was still asleep; and at the time when he was most fatally indulgent to his own sins, he was most ready to condemn the delinquencies and errors of others.
2 Kings (2 Samuel) 12:7
sa2 12:7HE APPLIES IT TO DAVID, WHO CONFESSES HIS SIN, AND IS PARDONED. (Sa2 12:7-23)
Nathan said to David, Thou art the man--These awful words pierced his heart, aroused his conscience, and brought him to his knees. The sincerity and depth of his penitent sorrow are evinced by the Psalms he composed (Psa 32:1-11; Psa. 51:1-19; Psa. 103:1-22). He was pardoned, so far as related to the restoration of the divine favor. But as from his high character for piety, and his eminent rank in society, his deplorable fall was calculated to do great injury to the cause of religion, it was necessary that God should testify His abhorrence of sin by leaving even His own servant to reap the bitter temporal fruits. David was not himself doomed, according to his own view of what justice demanded (Sa2 12:5); but he had to suffer a quadruple expiation in the successive deaths of four sons, besides a lengthened train of other evils.
2 Kings (2 Samuel) 12:8
sa2 12:8I gave thee thy master's house, and thy master's wives--The phraseology means nothing more than that God in His providence had given David, as king of Israel, everything that was Saul's. The history furnishes conclusive evidence that he never actually married any of the wives of Saul. But the harem of the preceding king belongs, according to Oriental notions, as a part of the regalia to his successor.
2 Kings (2 Samuel) 12:11
sa2 12:11I will raise up evil against thee out of thine own house, &c.--The prophet speaks of God threatening to do what He only permitted to be done. The fact is, that David's loss of character by the discovery of his crimes, tended, in the natural course of things, to diminish the respect of his family, to weaken the authority of his government, and to encourage the prevalence of many disorders throughout his kingdom.
2 Kings (2 Samuel) 12:15
sa2 12:15the Lord struck the child . . . and it was very sick--The first visible chastisement inflicted on David appeared on the person of that child which was the evidence and monument of his guilt. His domestics were surprised at his conduct, and in explanation of its singularity, it is necessary to remark that the custom in the East is to leave the nearest relative of a deceased person to the full and undisturbed indulgence of his grief, till on the third or fourth day at farthest (Joh 11:17). Then the other relatives and friends visit him, invite him to eat, lead him to a bath, and bring him a change of dress, which is necessary from his having sat or lain on the ground. The surprise of David's servants, then, who had seen his bitter anguish while the child was sick, arose apparently from this, that when he found it was dead, he who had so deeply lamented arose of himself from the earth, without waiting for their coming to him, immediately bathed and anointed himself, instead of appearing as a mourner, and after worshiping God with solemnity, returned to his wonted repast, without any interposition of others.
2 Kings (2 Samuel) 12:24
sa2 12:24SOLOMON IS BORN. (Sa2 12:24-25)
Bath-sheba . . . bare a son, and he called his name Solomon--that is, "peaceable." But Nathan gave him the name of Jedediah, by command of God, or perhaps only as an expression of God's love. This love and the noble gifts with which he was endowed, considering the criminality of the marriage from which he sprang, is a remarkable instance of divine goodness and grace.
2 Kings (2 Samuel) 12:26
sa2 12:26RABBAH IS TAKEN. (Sa2 12:26-31)
Joab fought against Rabbah--The time during which this siege lasted, since the intercourse with Bath-sheba, and the birth of at least one child, if not two, occurred during the progress of it, probably extended over two years.
2 Kings (2 Samuel) 12:27
sa2 12:27the city of waters--Rabbah, like Aroer, was divided into two parts--one the lower town, insulated by the winding course of the Jabbok, which flowed almost round it, and the upper and stronger town, called the royal city. "The first was taken by Joab, but the honor of capturing so strongly a fortified place as the other was an honor reserved for the king himself."
2 Kings (2 Samuel) 12:28
sa2 12:28encamp against the city, and take it--It has always been characteristic of Oriental despots to monopolize military honors; and as the ancient world knew nothing of the modern refinement of kings gaining victories by their generals, so Joab sent for David to command the final assault in person. A large force was levied for the purpose. David without much difficulty captured the royal city and obtained possession of its immense wealth.
lest I take the city, and it be called after my name--The circumstance of a city receiving a new name after some great person, as Alexandria, Constantinople, Hyderabad, is of frequent occurrence in the ancient and modern history of the East.
2 Kings (2 Samuel) 12:30
sa2 12:30he took their king's crown from off his head--While the treasures of the city were given as plunder to his soldiers, David reserved to himself the crown, which was of rarest value. Its great weight makes it probable that it was like many ancient crowns, not worn, but suspended over the head, or fixed on a canopy on the top of the throne.
the precious stones--Hebrew, "stone"; was a round ball composed of pearls and other jewels, which was in the crown, and probably taken out of it to be inserted in David's own crown.
2 Kings (2 Samuel) 12:31
sa2 12:31he brought forth the people . . . and put them under saws, &c.--This excessive severity and employment of tortures, which the Hebrews on no other occasion are recorded to have practised, was an act of retributive justice on a people who were infamous for their cruelties (Sa1 11:2; Amo 1:13).