صحيح مسلم بالإنكليزيةBook 6: The Book of Fasting (Kitab Al-Sawm) › Chapter 25: PERMISSIBILIY OF COMPLETING THE (MISSED) FASTS OF RAMADAN BEFORE THE COMMENCEMENT OF THE COMING RAMADAN
Abu Salama reported: I heard 'A'isha (Allah be pleased with her) as saying: I had to complete some of the fasts of Ramadan, but I could not do it but during the month of Sha'ban due to my duties to the Messenger of Allah (may peace be upon him) or with the Messenger of Allah (may peace be upon him).
