Sahih Bukhari
Sahih Bukhari Volume 003, Book 031, Hadith Number 132.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 31. Fasting
Narated By Ibn 'Umar : The Prophet said, "The month is like this and this," (at the same time he showed the fingers of both his hands thrice) and left out one thumb on the third time.