(81) باب صَوْمِ ثَلاَثَةِ أَيَّامٍ مِنَ الشَّهْرِ
Abu Hurairah said:
"The Messenger of Allah commanded me to pray two Rakahs of Duah,nt to sleep until after praying Witr and to fast three days of each month. (Sahih). (ID)
Reference (ID): Sunan an-Nasa'i 2406 (ID)
In-book reference (ID): Book 22, Hadith 317 (ID)
English translation (ID): Vol. 3, Book 22, Hadith 2408 (ID)