As related in this Hadīth, whenever the Prophet (may Allah's peace and blessings be upon him) set out for a battle, he would ask about a certain route other than the intended one so as to deceive the enemy and prevent spies from reporting their news. He wanted to reach the enemy while they were unprepared for the confrontation. An exception was the battle of Tabūk. As it would entail a long and arduous journey, he did not conceal the destination. And Allah, the Almighty, granted Muslims victory over the disbelievers.