Hadith 5:130
‘A'isha said that God’s messenger used to exert himself in devotion during the last ten nights to a greater extent than at any other time. Muslim transmitted it.
وَعَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَجْتَهِدُ فِي الْعَشْرِ الْأَوَاخِرِ مَا لَا يَجْتَهِدُ فِي غَيره. رَوَاهُ مُسلم
Original Reference: Mishkat al-Masabih 2089