Sahih Muslim , Book 42, Hadith 7089 (USC-MSA) ⓘ
'A'isha reported: We the family of Muhammad used to spend (the whole) month in which we (did not need to) kindle the fire as (we had nothing to cook) ; we had only dates and water (to fill our bellies).
حَدَّثَنَا عَمْرٌو النَّاقِدُ، حَدَّثَنَا عَبْدَةُ بْنُ سُلَيْمَانَ، قَالَ وَيَحْيَى بْنُ يَمَانٍ حَدَّثَنَا عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ إِنْ كُنَّا آلَ مُحَمَّدٍ صلى الله عليه وسلم لَنَمْكُثُ شَهْرًا مَا نَسْتَوْقِدُ بِنَارٍ إِنْ هُوَ إِلاَّ التَّمْرُ وَالْمَاءُ .
also referenced under: Book 55, Hadith 33 (In-Book) & Hadith 2972 (Reference)