Sahih Bukhari 1908 - The Book Of As-Saum (The Fasting)

Narrated Abu Huraira: The Prophet or Abul-Qasim said, Start fasting on seeing the crescent (of Ramadan), and give up fasting on seeing the crescent (of Shawwal), and if the sky is overcast (and you cannot see it), complete thirty days of Sha'ban. ..

Narrated Um Salama: The Prophet vowed to keep aloof from his wives for a period of one month, and after the completion of 29 days he went either in the morning or in the afternoon to his wives. Someone said to him You vowed that you would not go..

Narrated Anas: Allah's Apostle vowed to keep aloof from his wives for one month, and he had dislocation of his leg. So, he stayed in a Mashruba for 29 nights and then came down. Some people said, O Allah's Apostle! You vowed to stay aloof for one..

Narrated Abu Bakra: The Prophet said, The two months of `Id i.e. Ramadan and Dhul-Hijja, do not decrease (in superiority). ..

Narrated Ibn `Umar: The Prophet said, We are an illiterate nation; we neither write, nor know accounts. The month is like this and this, i.e. sometimes of 29 days and sometimes of thirty days. ..

Narrated Abu Huraira: The Prophet said, None of you should fast a day or two before the month of Ramadan unless he has the habit of fasting (Nawafil) (and if his fasting coincides with that day) then he can fast that day. ..