كتاب الإيمان
1  
The Book of Faith
(79)
Chapter: The saying of the Prophet (saws): "Allah does not sleep" and "His veil is light, and if he were to remove it, the splendour of his face would burn all of his creation, as far as hs sght reaches".
(79)
باب فِي قَوْلِهِ عَلَيْهِ السَّلاَمُ: «إِنَّ اللَّهَ لاَ يَنَامُ». وَفِي قَوْلِهِ: «حِجَابُهُ النُّورُ لَوْ كَشَفَهُ لأَحْرَقَ سُبُحَاتُ وَجْهِهِ مَا انْتَهَى إِلَيْهِ بَصَرُهُ مِنْ خَلْقِهِ»
Sahih Muslim 179 a

Abu Musa reported:

The Messenger of Allah (ﷺ) was standing amongst us and he told us five things. He said: Verily the Exalted and Mighty God does not sleep, and it does not befit Him to sleep. He lowers the scale and lifts it. The deeds in the night are taken up to Him before the deeds of the day, and the deeds of the day before the deeds of the night. His veil is the light. In the hadith narrated by Abu Bakr (instead of the word "light" ) it is fire. If he withdraws it (the veil), the splendour of His countenance would consume His creation so far as His sight reaches.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا أَبُو مُعَاوِيَةَ، حَدَّثَنَا الأَعْمَشُ، عَنْ عَمْرِو بْنِ مُرَّةَ، عَنْ أَبِي عُبَيْدَةَ، عَنْ أَبِي مُوسَى، قَالَ قَامَ فِينَا رَسُولُ اللَّهِ صلى الله عليه وسلم بِخَمْسِ كَلِمَاتٍ فَقَالَ ‏ "‏ إِنَّ اللَّهَ عَزَّ وَجَلَّ لاَ يَنَامُ وَلاَ يَنْبَغِي لَهُ أَنْ يَنَامَ يَخْفِضُ الْقِسْطَ وَيَرْفَعُهُ يُرْفَعُ إِلَيْهِ عَمَلُ اللَّيْلِ قَبْلَ عَمَلِ النَّهَارِ وَعَمَلُ النَّهَارِ قَبْلَ عَمَلِ اللَّيْلِ حِجَابُهُ النُّورُ - وَفِي رِوَايَةِ أَبِي بَكْرٍ النَّارُ - لَوْ كَشَفَهُ لأَحْرَقَتْ سُبُحَاتُ وَجْهِهِ مَا انْتَهَى إِلَيْهِ بَصَرُهُ مِنْ خَلْقِهِ ‏"‏ ‏.‏ - وَفِي رِوَايَةِ أَبِي بَكْرٍ عَنِ الأَعْمَشِ وَلَمْ يَقُلْ حَدَّثَنَا ‏.‏
Reference : Sahih Muslim 179a
In-book reference : Book 1, Hadith 350
USC-MSA web (English) reference : Book 1, Hadith 343
  (deprecated numbering scheme)