It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) set out on a military expedition and encountered the polytheists at Usfan. When the Messenger of Allah (peace and blessings be upon him) prayed the Zuhr prayer (with his Companions), and the polytheists saw him (peace and blessings be upon him) and the Companions bowing and prostrating together, they said to one another: "This was the best opportunity for you to attack; had you fallen upon them suddenly, they would not even have known of your intentions." Then one of them advised: "Indeed they have another prayer (Asr) coming, which is dearer to them than even their children and their wealth; so make full preparations so that you can attack them all at once at that time." On this occasion Allah, the Mighty and Majestic, revealed this verse to His Prophet (peace and blessings be upon him): "And when you are among them and lead them in prayer" [Surah al-Nisa': 102] , and Allah Almighty informed him (peace and blessings be upon him) of this plot of the polytheists. So when the Messenger of Allah (peace and blessings be upon him) led the Asr prayer while the polytheists were right in front, in the direction of the qiblah, he (peace and blessings be upon him) had the Muslims stand behind him in two rows. The Messenger of Allah (peace and blessings be upon him) said the opening takbir, and all of them said the takbir with him. Then the narrator described the complete method of the prayer of fear, and at its end he stated: When the polytheists saw that some of the Muslims were prostrating while others were standing and watching over them, they said (in astonishment): "They have certainly been informed of our intentions." This hadith is sahih (authentic) on the condition of Bukhari, but the two Shaykhs (Bukhari and Muslim) did not record it.