Abdullah bin Umar reported,

The Messenger of Allah ﷺ said, "The month is twenty-nine days." Shuba clapped his hands together three times, folding in his thumb on the third.Uqba said, "I think he also said, 'The month is thirty days,' and clapped his palms together three times."

Muslim 2510

Sahih

و حدثنا محمد بن المثنى حدثنا محمد بن جعفر حدثنا شعبة عن عقبة وهو ابن حريث قال سمعت

ابن عمر رضي الله عنهما يقول

ا قال رسول الله ﷺ الشهر تسع وعشرون وطبق شعبة يديه ثلاث مرار وكسر الإبهام في الثالثة قال عقبة وأحسبه قال الشهر ثلاثون وطبق كفيه ثلاث مرار

مسلم 2510صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Fasting
Chapter
Obligation of fasting Ramadan upon sighting Hilal and breaking the fast upon sighting Hilal, and that if it is obscured at its beginning or end the month is completed as thirty days
Numbering
Darussalam 2510
Muslim 2510