1- It is recommended that the followers do not stand up (to pray) until the call of iqama is over.
2- Straightening the rows of people praying and ordering others to do so, especially for the imam.
He must face the people and order them to straighten their rows.
Ibn Mas'oud Al-Badri (G. p. H) narrated: "The Messenger of Allah (P. B. U. H) used to place his hands over our shoulders when we lined up for prayer and say: "Make your rows straight and do not differ among yourselves, or your hearts will be in discord. '"
[Muslim, Vol. 1, The Book of Prayer, Chapter 28/122]. (pa: 230)
When only men (or women alone) are praying in congregation the best row is the first row then the second and so on.
Abu Hurayrah (G. p. H) narrated that the Prophet (P. B. U. H) said:
"If people knew the reward for the call to prayer and (standing in) the first row and there was no other way to get that reward but by drawing lots, they would do so"
[Al-Bukhari, Vol 1, The Book of Athan, Chapter 9/590].
It is preferred that women stand behind men when men and women are praying in congregation.
If a woman stands next to, or in front of, a man, then the prayer of
both is valid, though it is preferred that she stand behind him.
Abu Hurayrah (G. p. H) narrated that the Messenger of Allah (P. B. U. H) said:
"The best of men's rows is the first one and the worst is the last, and the best of women's rows is the last row and the worst is the first".
[Muslim, Vol. 1, The Book of Prayer, Chapter 28/132].
3- Brevity. The imam is recommended to make his prayer brief (Provided he performs the main and ordinary sunnas of prayer.
unless he is leading a congregation composed solely of those who do not mind a lengthy prayer.
Abu Hurayrah (G. p. H) narrated that the Messenger of Allah (P. B. U. H) said:
"When one of you leads the people in prayer, then let him make it brief for amongst them are the weak, the sick, and the old. And when one of you prays alone then let him make the prayer as long as he wishes".
[Al-Bukhari, Vol. 1, The Book of Congregational Prayer and the Inmate, Chapter 34/671].
4- The imam is recommended to raise his voice in takbir, in saying "Allah (G. B. H) hears whoever praises Him," and in salam, even in the silent prayer.
When reciting aloud he should intend thikr and informing together, since his prayer is invalidated if he lacks any intention or intends merely to inform.
5- When the imam is bowing or in the final testification of faith and becomes aware of someone coming to join the congregational prayer, it is recommended that he wait for the latecomer provided that the wait is not long and he does not favour a 'comer' over others.
No doubt, the permissibility of this wait is restricted by causing
the followers no harm, in accordance to the Prophet (P. B. U. H) command to make the congregational prayer brief.
6- It is recommended to repeat one's prescribed prayer with the congregation, making the intention of an obligatory prayer, whether one has performed the first alone, as a follower, or as an imam.
Jaber (G. p. H) said: "Mu'ath ibn Jabal (G. p. H) used to pray with the Prophet (P. B. U. H) and then go to lead his people in prayer".
[Al-Bukhari, Vol. 1, The Book of Congregational Prayer and the Inmate, Chapter 37/679].
The first counts as obligatory whereas the repeated one counts as a non-obligatory prayer.
Yazid ibn Al-Aswad, Al-A'miri narrated through his father:
"I joined the Prophet (P. B. U. H) in his hajj.
I performed with him Fajr prayer at Al-K Hayf mosque.
When he finished his prayer and turned, he saw two men in the back who did not pray, so he said:
"Let them come to me" (pa: 231)
They came trembling with fear.
He asked them: "Why you did not pray with us?"
They answered: '0 Messenger of Allah (P. B. U. H), we had already prayed at home. '
He said: "Do not do so. If you pray at home and then come to a mosque where a congregational prayer is being performed, then join the congregation and it will count as nafl"
[Al-Tinnithi, Vol. 1, The Books of Prayer, Chapter-163/219].
If one intends thereby to make up a missed prayer, then it is considered a make up, but if he makes the intention of repeating a prescribed prayer and recalls that he has committed a mistake in the first prayer, the second one is not valid and one has to intend to perform the prescribed prayer as though he had not performed it before.