Sunan Abi Dawud 2336
سنن أبي داود#2336SahihNarrated Umm Salamah, Ummul Mu'minin: She never saw the Prophet (ﷺ) fasting the whole month except Sha'ban which he combined with Ramadan
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 14:24