كتاب الصيام
13  
The Book of Fasting
(40)
Chapter: The virtue of Lailat Al-Qadr and the Exhortation to seek it; When it is and the most likely times to seek it
(40)
باب فَضْلِ لَيْلَةِ الْقَدْرِ وَالْحَثِّ عَلَى طَلَبِهَا وَبَيَانِ مَحَلِّهَا وَأَرْجَى أَوْقَاتِ طَلَبِهَا
Sahih Muslim 1168

'Abdullah b. Unais reported Allah's Messenger (ﷺ) as saying:

I was shown Lailat-ul-Qadr; then I was made to forget it, and saw that I was prostrating in water and clay in the morning of that (night). He (the narrator) said: There was a downpour on the twenty-third night and the Messenger of Allah (ﷺ) led us in prayer, and as he went back, there was a trace of water and clay on his forehead and on his nose. He (the narrator) said: 'Abdullah b. Unais used to say that it was the twenty-third (night).
وَحَدَّثَنَا سَعِيدُ بْنُ عَمْرِو بْنِ سَهْلِ بْنِ إِسْحَاقَ بْنِ مُحَمَّدِ بْنِ الأَشْعَثِ بْنِ قَيْسٍ، الْكِنْدِيُّ وَعَلِيُّ بْنُ خَشْرَمٍ قَالاَ حَدَّثَنَا أَبُو ضَمْرَةَ، حَدَّثَنِي الضَّحَّاكُ بْنُ عُثْمَانَ، - وَقَالَ ابْنُ خَشْرَمٍ عَنِ الضَّحَّاكِ بْنِ عُثْمَانَ، - عَنْ أَبِي النَّضْرِ، مَوْلَى عُمَرَ بْنِ عُبَيْدِ اللَّهِ عَنْ بُسْرِ بْنِ، سَعِيدٍ عَنْ عَبْدِ اللَّهِ بْنِ أُنَيْسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ أُرِيتُ لَيْلَةَ الْقَدْرِ ثُمَّ أُنْسِيتُهَا وَأَرَانِي صُبْحَهَا أَسْجُدُ فِي مَاءٍ وَطِينٍ ‏"‏ ‏.‏ قَالَ فَمُطِرْنَا لَيْلَةَ ثَلاَثٍ وَعِشْرِينَ فَصَلَّى بِنَا رَسُولُ اللَّهِ صلى الله عليه وسلم فَانْصَرَفَ وَإِنَّ أَثَرَ الْمَاءِ وَالطِّينِ عَلَى جَبْهَتِهِ وَأَنْفِهِ ‏.‏ قَالَ وَكَانَ عَبْدُ اللَّهِ بْنُ أُنَيْسٍ يَقُولُ ثَلاَثٍ وَعِشْرِينَ ‏.‏
Reference : Sahih Muslim 1168
In-book reference : Book 13, Hadith 281
USC-MSA web (English) reference : Book 6, Hadith 2631
  (deprecated numbering scheme)