It wasnarrated from Muhammad bin Sa'd bin Abu Waqqas that his fathersaid:
"The Messenger of Allah (ﷺ) said: 'The month is like thatandlike that and like that,' and he showed nine fingers on thethird timeto indicate twenty-nine."
English reference: Vol. 1, Book 7, Hadith 1657
Arabic reference: Book 7, Hadith 1726