Stand in rows and don’t lift hands while praying

Ṣaḥīḥ Muslim

4. The Book of Prayers

(27) Chapter:

The Command to Be Calm During the Prayer
And the Prohibition of Gesturing with One's Hand and Raising It When Saying the Salām;
And Completing the First Rows, Aligning In Them,
And the Command to Come Together

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Jabir b. Samura reported:

The Messenger of Allah () came to us and said:

"- How is it that I see you lifting your hands like the tails of headstrong horses? Be calm in prayer."

He (the narrator) said: He then again came to us and saw us (sitting) in circles. He said:

"- How is it that I see you in separate groups?"

He (the narrator) said: He again came to us and said:

"- Why don't you draw yourselves up in rows as angels do in the presence of their Lord?"

We said:

- Messenger of Allah, how do the angels draw themselves up in rows in the presence of their Lord?

He (the Holy Prophet) said:

"- They make the first rows complete and keep close together in the row."

Reference = Ṣaḥīḥ Muslim 430 a
In-book reference = Book 4, Hadith 130