´Abu Hurairah narrated:` "The Messenger of Allah took a covenant from me for three: To not sleep except after performing Witr, to fast three days of every month, and to perform the Duha prayer."
Hadith Referenceسنن ترمذي / كتاب الصيام عن رسول الله صلى الله عليه وسلم / 760
´Abu Dharr narrated that :` the Messenger of Allah said: "O Abu Dharr! When you fast three days out of a month, then fast the thirteenth, fourteenth, and fifteenth."
Hadith Referenceسنن ترمذي / كتاب الصيام عن رسول الله صلى الله عليه وسلم / 761
´Abu Dharr narrated:` "The Messenger of Allah said: 'Whoever fasts three days in every month, then that is (similar to) fasting every day.' Then Allah Mighty and Sublime is He, attested to that in His Book, by revealing: Whoever brings a good deed, shall have ten times the like thereof. So a day is like ten."
Hadith Referenceسنن ترمذي / كتاب الصيام عن رسول الله صلى الله عليه وسلم / 762
Hadith Gradingالألبانی:صحيح الإرواء أيضا | زبیر علی زئی:(762) إسناده ضعيف / ن 2411، جه 1708, أبو عثمان سمعه من رجل مجھول عن أبى ذربه
´Yazid Ar-Rishk said:` "I heard Mu'adhah saying to Aishah: 'Did the Messenger of Allah fast three days of every month?' She replied in the affirmative. So she said: 'Which of them would he fast?' She said: 'Which of them he would fast was not noticeable.'"
Hadith Referenceسنن ترمذي / كتاب الصيام عن رسول الله صلى الله عليه وسلم / 763