(7) باب فِي الْوِتْرِ قَبْلَ النَّوْمِ
Abu Al-Darda' said:
My friend (i.e. the Prophet) instructed me to observe three practices which I never leave: he instructed me to fast three days every month, and not to sleep but after observing the witr, and to observe supererogatory prayer in the forenoon while traveling and while resident.
Reference: Sunan Abi Dawud 1433
In-book reference: Book 8, Hadith 18
English translation: Book 8, Hadith 1428