عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا دَخَلَ الْعَشْرُ شَدَّ مِئْزَرَهُ، وَأَحْيَا لَيْلَهُ، وَأَيْقَظَ أَهْلَهُ.
Narrated Aisha: With the start of the last ten days of Ramadan, the Prophet (ﷺ) used to tighten his waist belt (i.e. work hard) and used to pray all the night, and used to keep his family awake for the prayers.
Bukhari