Albert Barnes Commentary 2 Samuel 12:16-17

"David therefore besought God for the child; and David fasted, and went in, and lay all night upon the earth. And the elders of his house arose, [and stood] beside him, to raise him up from the earth: but he would not, neither did he eat bread with them." — 2 Samuel 12:16-17 (ASV)

The death of an infant child born to one of the many wives of an ancient king would generally have been a matter of little concern to the father. David's deep feeling on this occasion, however, reveals both his affectionate and tender nature and also proves the strength of his passion for Bathsheba.

He went into his most private chamber, his 'closet' (Matthew 6:6), and lay upon the earth (2 Samuel 13:31). This means he lay on the ground—the floor of his chamber—as opposed to his couch.