Sunan an-Nasa'i, Volume 3, Book 22, Hadith 2137 (DarusSalam) ⓘ
It was narrated form Muhammad bin Sad Abi Waqqas, from his father, that: the Prophet struck one hand with the other and said: "The month is like this and like this and like this," retaining one finger the third time.
أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ، عَنْ إِسْمَاعِيلَ بْنِ أَبِي خَالِدٍ، عَنْ مُحَمَّدِ بْنِ سَعْدِ بْنِ أَبِي وَقَّاصٍ، عَنْ أَبِيهِ، عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ ضَرَبَ بِيَدِهِ عَلَى الأُخْرَى وَقَالَ " الشَّهْرُ هَكَذَا وَهَكَذَا وَهَكَذَا " . وَنَقَصَ فِي الثَّالِثَةِ إِصْبَعًا .
also referenced under: Hadith 2135 (Reference) & Book 22, Hadith 46 (In-Book)