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 يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ، عُمَرَ - رضى الله عنهما - عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " تَحَرَّوْا لَيْلَةَ الْقَدْرِ فِي السَّبْعِ الأَوَاخِرِ " .
Ibn 'Umar (Allah be pleased with them) reported Allah's Apostle (ﷺ) as saying: Seek Lailat-ul-Qadr in the last week (of Ramadan).
Reference : Sahih Muslim 1165bIn-book reference : Book 13, Hadith 268USC-MSA web (English) reference : Book 6, Hadith 2618