Abdullah bin Umar reported,

"Tonight is the night of the middle of the month."He said to him, "How do you know that tonight is the middle? I heard the Messenger of Allah ﷺ say, 'The month is like this and like this,' and he gestured with his fingers ten times twice, 'and like this' the third time, gesturing with all his fingers but holding back, or tucking in, his thumb."

Muslim 2513

Sahih

حدثنا أبو كامل الجحدري حدثنا عبد الواحد بن زياد حدثنا الحسن بن عبيد الله عن سعد بن عبيدة قال سمع

ابن عمر رضي الله عنهما رجلا يقول

الليلة ليلة النصف فقال له ما يدريك أن الليلة النصف سمعت رسول الله ﷺ يقول الشهر هكذا وهكذا وأشار بأصابعه العشر مرتين وهكذا في الثالثة وأشار بأصابعه كلها وحبس أو خنس إبهامه

مسلم 2513صحيح
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 2513
Muslim 2513