Jami` at-Tirmidhi 689
جامع الترمذي#689SahihIbn Mas`ud said:"What I fasted with the Prophet that was twenty-nine (days), was more than what we fasted that was thirty." (He said): There are narrations on this topic from `Umar, Abu Hurairah, `A'isha, Sa`d bin Abi Waqqas, Ibn `Abbas, Ibn `Umar, Anas, Jabir, Umm Salamah, Abu Bakrah, that the Prophet (ﷺ) said: "The month is twenty nine (days)
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
Zubair Ali ZaiIsnaad Sahih
In-book reference: 8:8