The Book of Fasting
13/40. Chapter:
The virtue of Lailat Al-Qadr and the Exhortation to seek it; When it is and the most likely times to seek it
Sahih Muslim
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنِ الشَّيْبَانِيِّ، عَنْ جَبَلَةَ، وَمُحَارِبٍ عَنِ ابْنِ عُمَرَ، - رضى الله عنهما - قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " تَحَيَّنُوا لَيْلَةَ الْقَدْرِ فِي الْعَشْرِ الأَوَاخِرِ " . أَوْ قَالَ " فِي التِّسْعِ الأَوَاخِرِ " .
'Ibn 'Umar (Allah be pleased with both of them) reported Allah's Messenger (ﷺ) as saying: Seek the time of Lailat-ul-Qadr in the last (ten nights), or he said: in the last nine (nights).
Reference : Sahih Muslim 1165gIn-book reference : Book 13, Hadith 273USC-MSA web (English) reference : Book 6, Hadith 2623