Mishkat al-Masabih 7 Fasting كتاب الصوم 130

وَعَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَجْتَهِدُ فِي الْعَشْرِ الْأَوَاخِرِ مَا لَا يَجْتَهِدُ فِي غَيره. رَوَاهُ مُسلم

‘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.