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 حدثنا عبد الواحد بن زياد قال حدثنا الحسن بن عبيد الله 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. Abdul-Wahid bin Ziyad is trustworthy, and his hadith is found in the collections of the group. Hasan bin Ubaydullah bin Urwa Nakhai is trustworthy, and his hadith is found in Muslim. The hadith has already appeared at 24258.