When asked about the fasting of the Prophet ﷺ, she said, "He used to fast until we would say he had truly committed himself to fasting, and he would break his fast until we would say he had stopped fasting altogether."She added, "The Messenger of Allah never fasted a complete month except Ramadan."
حدثنا قتيبة حدثنا حماد بن زيد عن أيوب عن عبد الله بن شقيق قال
عن صيام النبي ﷺ قالت كان يصوم حتى نقول قد صام ويفطر حتى نقول قد أفطر قالت وما صام رسول الله شهرا كاملا إلا رمضان
Muslim also narrated it, in the Book of Fasting, chapter on the fasting of the Prophet ﷺ outside of Ramadan, etc., hadith no. 174/1156, from the hadith of Hammad bin Zayd through the same chain.There is also a report on this subject from Anas [coming up: 769] and Ibn Abbas [Bukhari, no. 1971, and Muslim, no. 1157, and Tirmidhi in Shamail, no. 99].