The Importance of Congregation Prayer (Jamaat Namaaz)

Salat al-Jamaatat means praying in congregation, with one person leading. The Person who leads is called the Imam, while those who follow him are called the Ma'mum or Ma'mumin (plural). As for the daily prayers, the minimum amount of people needed is two -one, Imam and one Ma'mum. For the Salat al-Jumu'ah (Friday) there must be a minimum of five people, including the Imam.
There is no Salat al-Jama'at for the Mustahab Salat with the exception of Salat al-Istisqa " or the invocation for rain; and for the Salat of 'Eid, which are offered on the day of 'Eid al-Fitr and 'Eid al-Qurban, which are mustahab during the time of occultation of the 12th Imam (may our souls be sacrificed for him).
The Importance of Salat
The Salat is the most important act of worship in Islam, and if it is accepted by Allah (SWT), then all other acts of worship are accepted as well. However, if the Salat is not accepted, then all other actions also will not be accepted. It has been narrated from the 6th Imam, Jafar ibn Muhammad al-Sadiq, peace be upon him, quoting his forefathers up to the Messenger of Allah, peace be upon him and his family, that he said:

In Islam, perhaps there is no other Mustahab act that carries such benefits and results as Salat al-Jamaat. As for the importance of it, we quote one narration in which it has been mentioned that:

• If two people form a Jama'at, the reward for one Rak'at will be equal to one hundred and fifty prayers.

• If there are three people, the reward for one Rak'at will be equal to six hundred prayers.

• If there are four people, the reward for one Rak'at will be equal to one thousand two hundred prayers.

• If there are five people, the reward for one Rak'at will be equal to two thousand four hundred prayers, & such does the reward multiply, that if there are more than ten people in the Jama'at, then if all the skies were paper, all the seas were ink, all the trees were pens, and all the men, Jinn, and Angels got together as scribes to record the reward of one Rak'at, they would not be able to do it.

In the same narration, it is mentioned that the Takbir (Allahu Akbar) that the believers say after the leader of the salat is better and more beloved to Allah that sixty thousand Hajj and 'Umrah, and better than this world and all that is in it- sixty times over! Each Rak'at that the believer performs in Jama'at is better than offering one hundred thousand dinars in charity to the poor, and his sajdah is better than if he was to free one hundred slaves.

It is therefore, reprehensible to underestimate or ignore Salat al-Jama'at, and according to the Islamic rulings, it is not permitted to keep away oneself from the Salat al-Jama'at unduly, nor is it proper to abandon it without a justifiable excuse.

It is further Mustahab to wait for some time until the Salat al-Jama'at begins with the intention to participate in the Salat, since a short congregational Salat is better than a prolonged Salat offered alone. It is also better to wait for the Salat al-Jama'at to be established, even if it is offered after the prime time rather than to pray alone. In fact, if a person realizes that the Salat al-Jama'at has been established but he has already read his Salat, it is Mustahab to repeat the prayers again in Jama'at.

How to Join Salat al-Jamaat

Make the niyyat (intention) that you are praying behind and following the Imam who is leading the Salat. It is not necessary to know his name; however, you should know that you are following that particular Imam. Your Salat will not be counted as Salat al-Jamaat if you do not make the intention of following the Imam -this is important. The follower must say the Takbiratul Ihram after the Imam, so as to maintain his Salat al Jamaat.
Listen to the Imam
In the first two Rak'at, the Imam will read Surah al-Fatiha and one more complete Surah of the Holy Qur'an. If you are praying the Salat of Fajr, Maghrib and 'Isha, then the Imam will be reciting these Surahs out loud, thus, you should keep silent, and listen to his recitation. In the Salat of Zuhr and ‘Asr, the Imam will be reciting in a quiet whisper and you will not recite anything out loud.
Recite Everything Else in Jamaat
Apart from the two Surahs which the Imam alone will recite, you must independently recite all the other things in the Salat. You must pray the Dhikr of Ruku, Sujud, Tashahhud, Salam, and all the Takbirs, etc.

Follow the Imam
As was previously mentioned, the Ma’mum must say the Takiratul Ihram (the first) after the Imam has said it. If you say it simultaneously with the Imam or before, then there will be no Jamaat for you.
Then, in every act, follow the Imam. When the Imam goes into Ruku ' Sujud, or rises, do it either with him or after him; but do not precede him. This is important as far as the acts are concerned. However, in the case of the recitations like the Dhikr in Ruku', Sujud, Qunut, etc., you may precede the Imam, even the Salam to complete the Salat.
If you forgetfully rise from Ruku' or Sujud before the imam, you must return to the Ruku ' or Sajdah position (as the case may be) provided that the Imam is still in that position.
When Can You Join Salat al-Jamaat?
You can join the Salat at any stage before the Imam rises from Ruku'. After the Imam has risen from Ruku', you will not be able to join him until he stands for the next Rakat.

You cannot join the Imam while he is in Sajdah, nor can you join when the Imam stands up after completing the Ruku’.
Some Common Questions
Q. Can I join when the Imam is reciting the Second Surah?
A. Yes.
Q. Can I join when he is in Qunut?
A. Yes, you can join, and perform the Qunut as well.
Q. How do I join when the Imam is in Ruku '?
A. Make your intention, say the Takbiratul Ihram and go straight into Ruku'. This will be counted as your first Rak'at.
Q. How can I join when the Imam is in the third or fourth Rak'at?
A. In the third or fourth Rak'at, the Imam does not usually read Surah al- Fatiha nor is there a second Surah, he will usually recite Tasbihatul  Arbah. Therefore, if you join him while he is standing, you must read at least Surah al- Fatiha -you cannot simply keep silent. Therefore, if you believe that you will be able to read at least Surah al-Fatiha before the Imam goes into Ruku' and rises, you may join while he is standing. However if you believe that al-Fatiha may take a longer time to read and that you may miss the Ruku ' with the Imam, then do not join while the Imam is standing. In this case, join him when he goes into Rukuii ' .It is always advisable to join the Salat al-Jama'at in Ruku' if the Imam is in the third of fourth Rak'at.
Q. If I joined Salat al-Jamaat in the third Rak'at of the Imam, then what do I read in the next Rak'at which will be my second, but the Imam 's fourth?
A. You will treat it as your second and read surah al-Fatiha and another Surah, and do your best to reach the Imam while in Ruku'. If you find that there would not be enough time for the second Surah and Qunut, then Surah al-Fatiha alone will suffice.
Q. Should my Salat be the same as the Imam's?
A. No, you can pray Salat al-Maghrib, for example, behind an Imam who is leading Salat al-'Isha, and vice versa.
Q. What happens if a young child is standing in one of the rows? Does our Salat become void?

A. No, as long as the child is a Mummayiz, meaning he can distinguish between good and bad, and as long as the people around him do not have knowledge if his Salat has become void, their Salat al-Jama'at is correct.
Late Joiners
It is Mustahab to be present in Salat al-Jama'at from its very start. If fact, there is a great reward in being able to say the Takbiratul Ihram immediately after the Imam has said it, and before he commences the recitation of Surah al-Fatiha.
However, if due to some unavoidable circumstance, you reach late, then you will read as many Rak'at of Jama'at as available, and complete the balance on your own.
For example, if you reach Salat al-' Asr when the Imam is in his second Rak'at, then you will join, and when the Imam is in his last Rak'at, you will change your Salat to Furadah (single), and complete the remaining one Rak'at alone.
When it is your first Rak'at and the Imam's second, then according to Ihtiya1, after the two Sajdah, you must sit in a position, flexing your legs, keeping fingers and feet on the ground, and listen to the Tashahhud being recited by the Imam (this position is referred to as Tajafi).
Similarly, when it the last Rak'at of the Imam but you still have the balance to complete, it is Mustahab that you flex your legs with your fingers and feet still on the ground and wait until the Imam has finished reciting the Salam and then stand up to complete the Salat alone.
When a person arrives so late that he finds the Imam is in his last Tashahhud, he would still be able to obtain the reward of Jama'at. He should make the intention, say the Takbiratul Ihram and sit to join the Tashahhud. Then when the Imam has completed his Salat with the Salam, he should rise to begin the first Rak'at and he does not have to make the intention or say the Takbir again.
Source: Islamic-laws.com

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