Sahih
Muslim
صحيح مسلم
13
The Book of Fasting
كتاب الصيام
Chapter 26: It is Permissible to delay making up missed Ramadan Fasts until before the next Ramadan comes, and this is for those who broke the fast for a reason such as sickness, travel, menstruation and the like
باب قَضَاءِ رَمَضَانَ فِي شَعْبَانَ
Sahih Muslim 1146 b
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 (ﷺ).
وَحَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا بِشْرُ بْنُ عُمَرَ الزَّهْرَانِيُّ، حَدَّثَنِي سُلَيْمَانُ، بْنُ بِلاَلٍ حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، بِهَذَا الإِسْنَادِ غَيْرَ أَنَّهُ قَالَ وَذَلِكَ لِمَكَانِ رَسُولِ اللَّهِ صلى الله عليه وسلم .
Grade: Sahih