Ibn `Abbas reported that he spent a night in the house of his maternal aunt, Maimuna. The Messenger of Allah (ﷺ) got up at night and performed a short ablution (taking water) from the water-skin hanging there. (Giving a description of the ablution Ibn `Abbas said:

It was short and performed with a little water.) I also got up and did the same as the Messenger of Allah (ﷺ) had done. I then came (to him) and stood on his left. He then made me go around to his right side. He then observed prayer and went to sleep till he began to snore. Bilal came to him and informed him about the prayer. He (the Prophet) then went out and observed the dawn prayer without performing ablution. Sufyan said: It was a special (prerogative of the) Messenger of Allah (ﷺ) for it has been conveyed to us that the eyes of the Messenger of Allah (ﷺ) sleep, but his heart does not sleep.

حَدَّثَنَا ابْنُ أَبِي عُمَرَ، وَمُحَمَّدُ بْنُ حَاتِمٍ، عَنِ ابْنِ عُيَيْنَةَ، - قَالَ ابْنُ أَبِي عُمَرَ حَدَّثَنَا سُفْيَانُ، - عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ كُرَيْبٍ، مَوْلَى ابْنِ عَبَّاسٍ عَنِ ابْنِ عَبَّاسٍ، أَنَّهُ بَاتَ عِنْدَ خَالَتِهِ مَيْمُونَةَ فَقَامَ رَسُولُ اللَّهِ صلى الله عليه وسلم مِنَ اللَّيْلِ فَتَوَضَّأَ مِنْ شَنٍّ مُعَلَّقٍ وُضُوءًا خَفِيفًا - قَالَ وَصَفَ وُضُوءَهُ وَجَعَلَ يُخَفِّفُهُ وَيُقَلِّلُهُ - قَالَ ابْنُ عَبَّاسٍ فَقُمْتُ فَصَنَعْتُ مِثْلَ مَا صَنَعَ النَّبِيُّ صلى الله عليه وسلم ثُمَّ جِئْتُ فَقُمْتُ عَنْ يَسَارِهِ فَأَخْلَفَنِي فَجَعَلَنِي عَنْ يَمِينِهِ فَصَلَّى ثُمَّ اضْطَجَعَ فَنَامَ حَتَّى نَفَخَ ثُمَّ أَتَاهُ بِلاَلٌ فَآذَنَهُ بِالصَّلاَةِ فَخَرَجَ فَصَلَّى الصُّبْحَ وَلَمْ يَتَوَضَّأْ ‏.‏ قَالَ سُفْيَانُ وَهَذَا لِلنَّبِيِّ صلى الله عليه وسلم خَاصَّةً لأَنَّهُ بَلَغَنَا أَنَّ النَّبِيَّ صلى الله عليه وسلم تَنَامُ عَيْنَاهُ وَلاَ يَنَامُ قَلْبُهُ ‏.‏