Sahih Muslim Book - 3, Hadith - 763

و حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ أَخْبَرَنَا عَبْدُ الرَّزَّاقِ أَخْبَرَنَا مَعْمَرٌ عَنْ عَاصِمٍ عَنْ مُعَاذَةَ قَالَتْ سَأَلْتُ عَائِشَةَ فَقُلْتُ مَا بَالُ الْحَائِضِ تَقْضِي الصَّوْمَ وَلَا تَقْضِي الصَّلَاةَ؟ فَقَالَتْ أَحَرُورِيَّةٌ أَنْتِ قُلْتُ لَسْتُ بِحَرُورِيَّةٍ وَلَكِنِّي أَسْأَلُ، قَالَتْ: كَانَ يُصِيبُنَا ذَلِكَ فَنُؤْمَرُ بِقَضَاءِ الصَّوْمِ وَلَا نُؤْمَرُ بِقَضَاءِ الصَّلَاةِ.

It was narrated that Mu'adhah said: "I asked 'Aishah: 'Why does a menstruating woman have to make up missed fasts but not missed prayers?' She said: 'Are you a Haruriyyah?' I said: 'I am not a Haruriyyah, but I am asking.' She said: 'That used to happen to us and we were commanded to make up the fasts but we were not commanded to make up the prayers."'