Sahih Muslim
The Book of Fasting (Kitab Al-Sawm)
Book Number: 006 / Hadith Number: 2550
This hadith is narrated on the authority of Yahya b. Sa'id with the same chain of transmitters but with this variation that he said that ('A'isha did not observe fast but in Sha'ban) out of regard for the Messenger of Allah (may peace be upon him). (In another version, the words are):" Yahya said: I think it was due to the regard for the Apostle of Allah (may peace be upon him)."