Mukhtasar Muslim

Umm al-Mu'mineen Aisha Siddiqa (may Allah be pleased with her) says that when the last ten days of Ramadan would come, the Messenger of Allah (peace and blessings be upon him) would stay awake the whole night, wake up his family, strive hard (in worship), and tighten his waist belt (i.e., prepare himself with determination).