سنن النسائي

It was narrated from Ibn 'Umar that the Prophet (ﷺ) said: "The month is like this," and (one of the narrators) Shubah did the same gesture as Jabalah had done, copying, Ibn 'Umar: "It is twenty-nine, as he gestured twice with all fingers of both hands, and putting down one of his fingers the third time."