Will make him afraid. — This translation is hardly strong enough. The thought is that Ahithophel will throw his band into a panic by a sudden night attack, and in the confusion will easily secure the person of the king.
Related Commentaries of 2 Samuel 17:2
2 Samuel 17:2
2 And I will come upon him while he is weary and weak handed, and will make him afraid: and all the people that are with him shall flee; and I will smite the king only: