Therefore shalt thou fall in the day, and the prophet also shall fall with thee in the night, and I will destroy thy mother. Therefore shalt thou fall in the day - In the most open and public manner, without snare or ambush.
And the prophet also shall fall - in the night - The false prophet, when employed in taking prognostications from stars, meteors, etc.
And I will destroy thy mother - The metropolis or mother city. Jerusalem or Samaria is meant.