Sayyiduna Ka'b bin Malik (may Allah be pleased with him) said: Whenever the Messenger of Allah (peace and blessings be upon him) intended to undertake a battle, he would conceal (his intention) by ambiguity.
Hadith Referenceسنن دارمي / من كتاب السير / 2487
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده صحيح وابن المبارك هو: عبد الله، [مكتبه الشامله نمبر: 2494]
Hadith Takhrijاس روایت کی سند صحیح ہے۔ دیکھئے: [أبوداؤد 2636] ، [أحمد 456/3] ، [ابن أبى شيبه 18851]
Brief Explanation
(Commentary on Hadith 2486)
By "tawriyah" is meant that the actual intention is to go in one direction, but the indication and attention are directed elsewhere, so that the spy does not find out what the real plan is and the enemy does not become alert. For example, the intention is to go south, but for the purpose of gathering information or advancing, one moves towards the north or east, so that the enemy is caught unawares and in heedlessness. This is a military and wartime strategy; it cannot be called deception. The meaning of "al-harb khud'ah" is trickery and strategem, that is, whichever side acts with agility and cleverness in war, the outcome of the battle will be in their favor.