عَنْ عَائِشَةَ
قَالَتْ: كَانَ يَكُونُ عَلَيَّ الصَّوْمُ مِنْ رَمَضَانَ فَمَا أَسْتَطِيعُ أَنْ أَقْضِيَ إِلَّا فِي شَعْبَانَ. قَالَ يَحْيَى بْنُ سَعِيدٍ: تَعْنِي الشّغل من النَّبِي أَو بِالنَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ
Aishah said that when she had some part of the fast of Ramadan to make up she would be able to do so only in Shaban. Yahya ibn Said said she meant this was due to her being kept from it by her duty to the Prophet (sallallahu alayhi wa sallam).
Mishkat al-Masabih 1939, Book 8, Fasting, Hadith 73. 1 min read