Narrated by:Aishah, the Mother of the Believers, narrated:
"The Messenger of Allah visited me one day and said: 'Do you have anything (to eat)?'" She said: "I said: 'No.' He said: 'Then I am fasting.'"
حَدَّثَنَا هَنَّادٌ، حَدَّثَنَا وَكِيعٌ، عَنْ طَلْحَةَ بْنِ يَحْيَى، عَنْ عَمَّتِهِ، عَائِشَةَ بِنْتِ طَلْحَةَ عَنْ عَائِشَةَ أُمِّ الْمُؤْمِنِينَ، قَالَتْ دَخَلَ عَلَىَّ رَسُولُ اللَّهِ صلى الله عليه وسلم يَوْمًا فَقَالَ " هَلْ عِنْدَكُمْ شَيْءٌ " . قَالَتْ قُلْتُ لاَ . قَالَ " فَإِنِّي صَائِمٌ " .
Tirmizi
The Book on Fasting • Hadith 732