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 1165 c

Arabic hadith text
وَحَدَّثَنِي عَمْرٌو النَّاقِدُ، وَزُهَيْرُ بْنُ حَرْبٍ، قَالَ زُهَيْرٌ حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، - رضى الله عنه - قَالَ رَأَى رَجُلٌ أَنَّ لَيْلَةَ الْقَدْرِ لَيْلَةُ سَبْعٍ وَعِشْرِينَ ‏.‏ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏أَرَى رُؤْيَاكُمْ فِي الْعَشْرِ الأَوَاخِرِ فَاطْلُبُوهَا فِي الْوِتْرِ مِنْهَا ‏"
Translation
Salim reported on the authority of his father that a person saw Lailat-ul- Qadr on the 27th (of Ramadan). Thereupon Allah's Apostle (ﷺ) said

I see that your dreams agree regarding the last ten (nights of Ramadan). So seek it on an odd number (of these ten nights).