´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