السلام
كلمة (السلام) في اللغة مصدر من الفعل (سَلِمَ يَسْلَمُ) وهي...
Ka‘b ibn Mālik (may Allah be pleased with him) reported: Whenever the Messenger (may Allah's peace and blessings be upon him) intended to carry out a battle, he would use an equivocation to conceal his real destination till it was the battle of Tabūk which the Messenger carried out in very hot weather. As he was going to face a very long journey through a wasteland and was to meet and attack a large number of enemies. So, he made the situation clear to the Muslims so that they might prepare themselves accordingly and get ready to conquer their enemy. The Prophet (may Allah's peace and blessings be upon him) informed them of the destination he was heading for.
شرح الحديث :
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.