Charles Ellicott Commentary 1 Samuel 25:37

"And it came to pass in the morning, when the wine was gone out of Nabal, that his wife told him these things, and his heart died within him, and he became as a stone." — 1 Samuel 25:37 (ASV)

When the wine was gone out. —Simply, when the brutish, selfish reveller had become sober through the passage of time.

His heart died within him. —These words are generally understood as indicating that an attack of apoplexy (a stroke) had seized the intemperate man. Commentators are somewhat divided as to the immediate cause of the stroke.

1. It was brought on by fear, upon learning of the terrible danger to which he had been exposed through his reckless, unguarded language and churlish conduct. In that drunken sleep, from which he had then scarcely awakened, he and all his family would have perished miserably if it had not been for his wife’s forethought. In his enfeebled state, still feverish and excited from the strong drink, terror and horror seized him, and the "stroke" followed.
2. A furious burst of anger at his wife’s news swept over him. That she should have humiliated herself before David, one whom he evidently hated, was unbearable to him. The wild burst of anger, acting on his ruined, drink-shattered body, completed the damage, and the result was the stroke of apoplexy.

The first cause is, however, the more probable.