Sunan an-Nasa'i 2134
سنن النسائي#2134SahihIt was narrated that Ibn 'Abbas said:"The Messenger of Allah 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:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 22:45