Imam Ahmad ibn Hanbal, may Allah have mercy on him, said: “Every hadith narrated concerning the various forms of the Prayer of Fear may be acted upon. Six or seven forms have been reported regarding it.”
Mujahid (1) said concerning the occasion for the revelation of this verse, on the authority of Ibn Ayyash al-Zuraqi: “We were with the Messenger of Allah, peace and blessings be upon him, at Usfan, while Khalid ibn al-Walid was in command of the polytheists. We performed the Zuhr prayer, and the polytheists said, ‘We had an opportunity against them; if only we had attacked them while they were praying!’ So the verse was revealed between Zuhr and Asr.”
Regarding His saying, Exalted is He: “When you are among them”—that is, present with them and leading them in prayer—“let a group of them stand with you”: that is, let them stand, as in His saying, Exalted is He, “but when darkness comes over them, they stand still” (al-Baqarah, 20), meaning that they stop. “And let them take their weapons.” There is disagreement over those who are to take their weapons. Some said that it refers to those standing with the imam in prayer: they are to take their weapons during the prayer. According to this view, one should carry a weapon only if it does not distract him from the prayer or harm the person beside him. [If its movement distracts him or its weight burdens him in the prayer, such as a quiver or a large shield, or if it harms the person beside him] (2), such as a spear, then he should not carry it.
It was also said that “let them take their weapons” refers to those remaining opposite the enemy. “Then, when they have prostrated”—that is, completed their prayer—“let them be behind you,” meaning that they should take the place of those facing the enemy. “Then let another group, who have not yet prayed,” namely those who had been facing the enemy, “come and pray with you, taking their precautions and their weapons.” It was said that this refers to the group that came forward, and it was also said that it refers to those who had prayed. “The disbelievers wish”: that is, the disbelievers desire “that you would neglect your weapons and baggage, so that they could descend upon you in a single assault”—that is, they would set upon you and charge you all at once.
“And there is no blame upon you if you are troubled by rain or are ill, for laying down your weapons.” A concession was granted to lay down one’s weapons in the case of rain or illness, because weapons are burdensome to carry in both circumstances. “But take your precautions”: that is, keep watch over the enemy, lest they catch you unawares. Precaution is that by which one guards oneself against the enemy.
Al-Kalbi narrated from Abu Salih, from Ibn Abbas, may Allah be pleased with him, that it was revealed concerning the Messenger of Allah, peace and blessings be upon him. This was because he campaigned against Muharib and Banu Anmar. They encamped without seeing anyone from the enemy, so the people laid down their weapons. The Messenger of Allah, peace and blessings be upon him, went out for a need of his after laying aside his weapons. He crossed the valley while the sky was lightly raining, and the valley came between the Messenger of Allah, peace and blessings be upon him, and his Companions. The Messenger of Allah, peace and blessings be upon him, sat in the shade of a tree. Ghawrath ibn al-Harith al-Muharibi saw him and said, “May Allah kill me if I do not kill him!” He then descended from the mountain carrying a sword. The Messenger of Allah, peace and blessings be upon him, did not notice him until he was standing over him with his sword drawn from its sheath. He said, “O Muhammad, who will protect you from me now?” The Messenger of Allah, peace and blessings be upon him, replied, “Allah.” Then he said, “O Allah, protect me...”