Sunan Ibn Majah
1649
Sahih+3

It was narrated that Rabi’ah bin Ghaz asked ‘Aishah about the fasting of the Messenger of Allah (ﷺ). She said:“He used to fast all of Sha’ban, until he joined it to Ramadan.”

SahihAl-Albani
Hasan SahihMuhammad Fouad Abd al-Baqi