´It was narrated from Muhammad bin Sa’d bin Abu Waqqas that his father said:` “The Messenger of Allah (ﷺ) said: ‘The month is like that and like that and like that,’ and he showed nine fingers on the third time to indicate twenty-nine.”
Hadith ReferenceSunan Ibn Majah / The Book of Fasting / Hadith: 1657
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:صحيح مسلم