Sunan Abi Dawud 2325
سنن أبي داود#2325SahihNarrated Aisha, Ummul Mu'minin: The Messenger of Allah (ﷺ) used to count the days in Sha'ban in a manner he did not count any other month; then he fasted when he sighted the new moon of Ramadan; but if the weather was cloudy he counted thirty days and then fasted
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
Shuaib Al ArnautHasan Sahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 14:13