Adam Clarke on 2 Samuel 24:15

From the morning - to the time appointed - That is, from the morning of the day after David had made his election till the third day, according to the condition which God had proposed, and he had accepted: but it seems that the plague was terminated before the conclusion of the third day, for Jerusalem might have been destroyed, but it was not. Throughout the land, independently of the city, seventy thousand persons were slain! This was a terrible mortality in the space of less than three days.