Sahih Muslim Book 6, Hadith Number 2550.

Chapter : Permissibility of completing the fasts of Ramadhan before the commencement of the coming Ramadhan.

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 (‘Aisha 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).”