After (the excitement) of the distress, He sent down calm on a band of you overcome with slumber, while another band was stirred to anxiety by their own feelings, Moved by wrong suspicions of Allah-suspicions due to ignorance. They said: "What affair is this of ours?" Say thou: "Indeed, this affair is wholly Allah's." They hide in their minds what they dare not reveal to thee. They say (to themselves): "If we had had anything to do with this affair, We should not have been in the slaughter here." Say: "Even if you had remained in your homes, those for whom death was decreed would certainly have gone forth to the place of their death"; but (all this was) that Allah might test what is in your breasts and purge what is in your hearts. For Allah knoweth well the secrets of your hearts. Ali 'Imran 3:154 ⧉
Tafsir:
The most important thing for the believer, in life’s trials and tribulations, is to remain calm and composed, so that he may draw up his plans with full concentration. Such composure and concentration derive from complete trust placed in God. Even on the most earth-shaking of occasions, when people find it impossible to sleep, the believers are able to revitalize themselves with the soothing effect of sleep. This was demonstrated on the occasion of Uhud when, despite the severest of conditions, they were able to have a good night’s sleep. Rested and refreshed, they then pursued the enemy forces as far as Hamraul-Asad, some eight miles from Madinah. Severely wounded and defeated, they would not have been able to take any further action, had calm not descended upon them. This hot pursuit awed the enemy, who turned about and retreated to Makkah. This is the state in which the believers live, whereas those who have not made God their guardian and protector in the full sense of these words, inevitably fear for their own lives. Bereft of any concern for religion, they are engrossed in their own selves. Such people are never blessed with composure through divine succour.