This night - The night of the day on which David fled, and Absalom entered into Jerusalem. Ahithophel’s idea was to fall upon David by surprise, and in the first confusion of the surprised army to seize and kill David only.
Related Commentaries of 2 Samuel 17:1
2 Samuel 17:1
1 Moreover Ahithophel said unto Absalom, Let me now choose out twelve thousand men, and I will arise and pursue after David this night: