When you (Mohammad) stand to worship your Lord in the midst of a military campaign, let a party of your troops join you in prayer, with their arms besides. When they finish their prayers, put them on guard so that the others join you in worship. You may leave your arms apart if you are too sick [or injured] or the weather is too inclement (making it too difficult for you to carry the arm) as long as you remain alert. Beware that your enemies wish to take advantage of your slightest relaxation to finish you all up. Rest assured that God has prepared a disgraceful punishment for the disbelievers.