The man whom thou seekest - namely, David. Ahithophel means to say: “If I can only smite David, there will be no civil war, all the people will peaceably submit.”
Related Commentaries of 2 Samuel 17:3
2 Samuel 17:3
3 And I will bring back all the people unto thee: the man whom thou seekest is as if all returned: so all the people shall be in peace.