Aisha was asked about the fasting of the Prophet ﷺ. She replied, "He used to fast until we would say he would never break his fast, and he would refrain from fasting until we would say he would never fast. I never saw him fast in any month more than he fasted in Shaban. He used to fast all of Shaban. He used to fast Shaban except for a little."
حدثنا أبو بكر بن أبي شيبة حدثنا سفيان بن عيينة عن ابن أبي لبيد عن أبي سلمة قال
عن صوم النبي ﷺ فقالت كان يصوم حتى نقول قد صام ويفطر حتى نقول قد أفطر ولم أره صام من شهر قط أكثر من صيامه من شعبان كان يصوم شعبان كله كان يصوم شعبان إلا قليلا
Narrated by Muslim, in the Book of Fasting, chapter on the fasting of the Prophet ﷺ outside Ramadan, hadith no. 1156, etc., from Abu Bakr bin Abu Shayba and others, through this chain. Bukhari also narrated it, hadith no. 1969, and others, through another route from Abu Salama, through this chain.