And Nathan departed unto his house. And the LORD struck the child that Uriah's wife bare unto David, and it was very sick.

Jamieson-Fausset-Brown Bible Commentary

15-23. the 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.

Matthew Henry's Concise Commentary

12:15-25 David now penned the 51st Psalm, in which, though he had been assured that his sin was pardoned, he prays earnestly for pardon, and greatly laments his sin. He was willing to bear the shame of it, to have it ever before him, to be continually upbraided with it. God gives us leave to be earnest with him in prayer for particular blessings, from trust in his power and general mercy, though we have no particular promise to build upon. David patiently submitted to the will of God in the death of one child, and God made up the loss to his advantage, in the birth of another. The way to have creature comforts continued or restored, or the loss made up some other way, is cheerfully to resign them to God. God, by his grace, particularly owned and favoured that son, and ordered him to be called Jedidiah, Beloved of the Lord. Our prayers for our children are graciously and as fully answered when some of them die in their infancy, for they are well taken care of, and when others live, beloved of the Lord.