Performing A Voluntary Fast Without Planning It The Night Before Jami` at-Tirmidhi 733
Arabic hadith text
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 "
Translation
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.'"