‘A'isha said:

The Prophet (ﷺ) came to visit me one day and asked if I had anything [to eat]. When I said I had nothing he replied, “Then I shall observe a fast.” When he came to me another day and I told him I had been given a present of some <i>hais</i>* he said, “Show me it, for I began the day fasting.” Then he ate. *A mixture of dates and clarified butter. Muslim transmitted it.

وَعَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ: دَخَلَ عَلَيَّ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ذَاتَ يَوْمٍ فَقَالَ: «هَلْ عِنْدَكُمْ شَيْءٌ؟» فَقُلْنَا: لَا قَالَ: «فَإِنِّي إِذًا صَائِمٌ» . ثُمَّ أَتَانَا يَوْمًا آخَرَ فَقُلْنَا: يَا رَسُولَ اللَّهِ أُهْدِيَ لَنَا حَيْسٌ فَقَالَ: «أَرِينِيهِ فَلَقَدْ أَصْبَحْتُ صَائِمًا» فَأَكَلَ. رَوَاهُ مُسلم