we used to pray along with the Messenger of Allah (ﷺ) in intense heat. When any of us could not rest his face on bare ground while prostrating due to intense heat he spread his cloth and would prostrate on it.
Why do you stand in rows as the angels do in the presence of their Lord? We asked: how do the angles stand in rows in the presence of their Lord? He replied: they make the first row complete and keep close together in the row.
the Messenger of Allah (ﷺ) paid attention to the people and said three times; straighten your rows (in prayer); by Allah, you must straighten your rows, or Allah will certainly put your faces in contrary directions. I then saw that every person stood in prayer keeping his shoulder close to that of the other, and his knee close to that of the other, and his ankle close to that of the other.
the prophet (ﷺ) used to straighten us in the rows of prayer as the arrow is straightened, until he thought that we had learned it from him and understood it. One day he turned towards us, and shoulders in order, and say; Do not be irregular. And he would say: Allah and his Angels bless those who near the first rows.
The Messenger of Allah (ﷺ) used to pass through the row from one side to the other; he used to set out chests and shoulders in order, and say: Do not be irregular. And he would say: Allah and His angels bless those who are near the first rows.
The Prophet (ﷺ) said: Set the rows in order, stand shoulder to shoulder, close the gaps, be pliant in the hands of your brethren, and do not leave openings for the devil. If anyone joins up a row, Allah will join him up, but if anyone breaks a row, Allah will cut him off. Abu Dawud said: The name of Abu Shjrah is Kathir b. Murrah.
The Prophet (ﷺ) said: Stand close together in your rows, bring them near one another, and stand neck to neck, for by Him in Whose hand my soul is, I see the devil coming in through openings in the row just like a small black sheep.
one day I prayed by the side of Anas b. Malik. He said ; Do you know why this stick is placed here ? I said : No, by Allah. He said; The Messenger of Allah (ﷺ) used to put his hand upon it and say: Keep straight and straighten your rows.