(70) باب صَوْمِ النَّبِيِّ صلى الله عليه وسلم - بِأَبِي هُوَ وَأُمِّي - وَذِكْرِ اخْتِلاَفِ النَّاقِلِينَ لِلْخَبَرِ فِي ذَلِكَ
It was narrated that Abu Hurairah said:
"The Messenger of Allah commanded me to pray two Rakahs of Duha, and not to sleep until I had prayed witr, and to fast three days each month."
Reference: Sunan an-Nasa'i 2369
In-book reference: Book 22, Hadith 280
English translation: Vol. 3, Book 22, Hadith 2371