Surah al-A`raf (The Elevated Places) 7 : 4

Explanatory Note

The destruction of past nations and communities serves as a very good reminder and warner. The fact that they were so severely punished is utilized in the Qur’ān as an inspiring element which should alert human minds that have so far been oblivious of their situation and their duty. Numerous have been those communities which were destroyed because of their rejection of the message of the truth. Invariably, they were taken unawares, either in the dead of the night or at midday when people relax and sleep, feeling a sense of security: “How many a community have We destroyed, with Our punishment falling upon them by night, or at midday while they were resting.” (Verse 4)
 
Both the depth of the night and the middle of the day when people have their siesta are normally thought of as periods of security, when people can relax and sleep. To be punished so severely at this particular time sounds much more horrific. It should also serve as a stronger reminder, helping people to take more heed.
 
What happened then? Those people who were taken unaware could do nothing other than to own up to their situation and confess to the attitude they had taken.