The Messenger of Allah ﷺ used to strive during the last ten nights with an effort he did not exert at any other time.
حدثنا عفان قال حدثنا عبد الواحد بن زياد قال حدثنا الحسن بن عبيد الله قال حدثنا إبراهيم عن الأسود بن يزيد
كان رسول الله ﷺ يجتهد في العشر ما لا يجتهد في غيره
No references are available.
Its isnad is sahih. Hasan bin Abdullah is Nakhai, one of the reliable and excellent hadith scholars. His hadith is found in Muslim, and the hadith previously appeared at 24409.