Sahih Muslim
The Book of Fasting (Kitab Al-Sawm)
Book Number: 006 / Hadith Number: 2577
'Abdullah b. Shaqiq reported: I said to 'A'isha (Allah be pleased with her): Did the Messenger of Allah (may peace be upon him) observe fast during a month? She said, I do not know of any month in which he fasted throughout except Ramedan and (the month) in which he did not fast at all till he ran the course of his life. May peace be upon him.