Sahih Muslim 1146
Sahih Muslim · Book 13: The Book of Fasting · 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
'A'isha reported:
وَحَدَّثَنِي مُحَمَّدُ بْنُ أَبِي عُمَرَ الْمَكِّيُّ ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ مُحَمَّدٍ الدَّرَاوَرْدِيُّ ، عَنْ يَزِيدَ بْنِ عَبْدِ اللَّهِ بْنِ الْهَادِ ، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ ، عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ ، عَنْ عَائِشَةَ ، - رضى الله عنها - أَنَّهَا قَالَتْ إِنْ كَانَتْ إِحْدَانَا لَتُفْطِرُ فِي زَمَانِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَمَا تَقْدِرُ عَلَى أَنْ تَقْضِيَهُ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم حَتَّى يَأْتِيَ شَعْبَانُ .
If one amongst us had to break fasts (of Ramadan due to natural reasons, i. e. menses) during the life of the Messenger of Allah (ﷺ) she could not find it possible to complete them so long she had been in the presence of Allah's Messenger (ﷺ) till Sha'ban commenced.