Muwatta Malik, Book 18, Hadith 683 (In-Book) ⓘ

Yahya related to me from Malik from Ibn Shihab that A'isha and Hafsa, the wives of the Prophet, may Allah bless him and grant him peace, began fasting voluntarily one morning and then food was given to them and they broke their fast with it. Then the Messenger of Allah, may Allah bless him and grant him peace, came in. A'isha said, "Hafsa asked, anticipating me in speech - she took after her father Umar - 'Messenger of Allah, A'isha and I began the morning fasting voluntarily and then food was given us and we broke the fast with it.' The Messenger of Allah, may Allah bless him and grant him peace, said, 'Fast another day in its place.' "

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، أَنَّ عَائِشَةَ، وَحَفْصَةَ، زَوْجَىِ النَّبِيِّ صلى الله عليه وسلم أَصْبَحَتَا صَائِمَتَيْنِ مُتَطَوِّعَتَيْنِ فَأُهْدِيَ لَهُمَا طَعَامٌ فَأَفْطَرَتَا عَلَيْهِ فَدَخَلَ عَلَيْهِمَا رَسُولُ اللَّهِ صلى الله عليه وسلم قَالَتْ عَائِشَةُ فَقَالَتْ حَفْصَةُ وَبَدَرَتْنِي بِالْكَلاَمِ - وَكَانَتْ بِنْتَ أَبِيهَا - يَا رَسُولَ اللَّهِ إِنِّي أَصْبَحْتُ أَنَا وَعَائِشَةُ صَائِمَتَيْنِ مُتَطَوِّعَتَيْنِ فَأُهْدِيَ إِلَيْنَا طَعَامٌ فَأَفْطَرْنَا عَلَيْهِ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ اقْضِيَا مَكَانَهُ يَوْمًا آخَرَ ‏" ‏ ‏.‏