Jami` at-Tirmidhi 768
جامع الترمذي#768SahihAbdullah bin Shaqiq narrated:"I asked Aishah about the Prophet's fasting.' She said: 'He would fast until we said: "He has fasted" and he would abstain from fasting until we said: "He has abstained from fasting." (She said:) 'The Messenger of Allah did not fast an entire month except Ramadan
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiSahih - Bukhari And Muslim
In-book reference: 8:87