وعنها قالت: كان رسول الله صلى الله عليه وسلم، يجتهد في رمضان ما لا يجتهد في غيره، وفي العشر الأواخر منه، ما لا يجتهد في غيره
The Messenger of Allah (sallallahu alayhi wa sallam) used to strive more in worship during Ramadan than he strove in any other time of the year; and he would devote himself more (in the worship of Allah) in the last ten nights of Ramadan than he strove in earlier part of the month.
Riyad as-Salihin 1194, Book 9, The Book of Virtues, Hadith 204. 1 min read