Riyad as-Salihin 1247
'Aishah (May Allah be pleased with her) reported:
The Prophet (ﷺ) did not observe voluntary Saum (fasting) so frequently during any other month as he did during Sha'ban. He observed Saum throughout the month of Sha'ban. Another narration is: He (ﷺ) observed Saum during the whole month of Sha'ban except a few days. [Al- Bukhari and Muslim] .
وعن عائشة رضي الله عنها قالت لم يكن النبي صلى الله عليه وسلم يصوم من شهر أكثر من شعبان فإنه كان يصوم شعبان كله وفي رواية‏:‏ كان يصوم شعبان إلا قليلا‏.‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏