Jabir bin Samura reported,

The Messenger of Allah ﷺ came out to us and said, "Why do I see you raising your hands as though they were the tails of restless horses? Be still in prayer."Then he came out to us again and saw us sitting in scattered circles, so he said, "Why do I see you in separate groups?"Then he came out to us and said, "Will you not form your rows as the angels form theirs before their Lord?"We asked, "Messenger of Allah, how do the angels form their rows before their Lord?"He answered, "They complete the first rows and press close together in the row."

Muslim 969

Sahih

و حدثني أبو سعيد الأشج حدثنا وكيع ح و حدثنا إسحق بن إبراهيم أخبرنا عيسى بن يونس قالا جميعا حدثنا الأعمش بهذا الإسناد نحوه

مسلم 969صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Prayer
Chapter
Command to be still during prayer, prohibition of gesturing and raising the hand when giving salam, completing the front rows and standing close together in them, and command to gather
Numbering
Darussalam 969
Muslim 969