وَحَدَّثَنِي أَبُو الرَّبِيعِ الزَّهْرَانِيُّ، حَدَّثَنَا حَمَّادٌ، عَنْ أَيُّوبَ، وَهِشَامٍ، عَنْ مُحَمَّدٍ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، - قَالَ حَمَّادٌ وَأَظُنُّ أَيُّوبَ قَدْ سَمِعَهُ مِنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، - قَالَ سَأَلْتُ عَائِشَةَ - رضى الله عنها - عَنْ صَوْمِ النَّبِيِّ صلى الله عليه وسلم فَقَالَتْ كَانَ يَصُومُ حَتَّى نَقُولَ قَدْ صَامَ قَدْ صَامَ ‏.‏ وَيُفْطِرُ حَتَّى نَقُولَ قَدْ أَفْطَرَ قَدْ أَفْطَرَ - قَالَتْ - وَمَا رَأَيْتُهُ صَامَ شَهْرًا كَامِلاً مُنْذُ قَدِمَ الْمَدِينَةَ إِلاَّ أَنْ يَكُونَ رَمَضَانَ ‏.‏

Abdullah b. Shaqiq reported. I asked 'A'isha (Allah be pleased with her) about fasting of the Messenger of Allah (PBUH). She said: He used to observe fast (at times) so continuously that we said: He has fasted, he has fasted. And (at times) he did not observe fast (for days) and we began to say: He has abandoned fasting, he has abandoned fasting. She said: I did not see him observing fast throughout the whole of the month since he arrived in Medina, but that of Ramadan. Translation Not Available

Book Ref: Sahih Muslim Book 13 Hadith 2578
Web Ref:  Sahih Muslim Book 6 Hadith 1156 c