Riyad as-Salihin, Book 9, Hadith 1247 (In-Book) ⓘ
'Aishah (May Allah be pleased with her) reported: The Prophet 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 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))